adventure: Tier 6 postgame "Mythic" dungeons (P1–P7 calibration)

Five post-game dungeons above the T5 ceiling, gated on both T5 bosses beaten
+ level 18. Opt-in endgame: deadly solo, clearable by a party with Pete + pets.

- P1 gating: postgameUnlocked (T5 clears + level floor), zonesForLevel excludes
  T6 unconditionally; wired into startZoneRun, !zone/!expedition, party accept,
  boredom picker, and the list dividers.
- P2 bestiary: 15 elites + 5 signature bosses (Layer-1 stat blocks).
- P3 zone defs + 4-region registries; ZoneLootEntry.BossOnly.
- P4 five zone graphs on a shared builder (44–52 rooms, no soft-lock; Ossuary
  secret Verse nodes).
- P5 loot: BossOnly enforced; signature items are real registry magic items;
  five Thom pity recipes off the per-zone crafting anchors.
- P6 narration/flavor (5 files), T6 achievements, Pete stays zone-parametric.
- P7 (in progress): sim can now reach gated T6 (SimRunner.SeedPostgameUnlock +
  IsPostgameZone). First calibration pass on millenia — hardened ossuary +
  drowned_star, softened first_hoard + unplace; last_meridian in band.

Fix: party members were refused from every T6 zone because expeditionCmdAccept
ran the level gate (which excludes T6) before the postgame check — the intended
party endgame was unreachable. Route T6 through postgameUnlocked. Regression
tests added.

internal/flavor/zone_first_hoard_flavor.go

@@ -0,0 +1,61 @@
+// DO NOT REWRITE, SUMMARIZE, OR SHORTEN ANY ENTRIES IN THIS FILE
+// zone_first_hoard_flavor.go
+// Tier 6 post-game zone flavor — The First Hoard. Additive only.
+
+package flavor
+
+// ROOM ENTRY
+var RoomEntryFirstHoard = []string{
+	"You climb over what used to be Infernax. His corpse is the floor now — a red slope of cooling scale wide enough to march a company across. The heat coming off him is residual, I think. I file this under 'the mountain is still digesting a dragon' and keep moving.",
+	"The throne room is carpeted in coins, and every coin faces up, and every coin shows the same face. Nobody minted these. They grew. I track the pattern and recommend you stop looking for the pattern.",
+	"A corridor of gold leaf so thin it moves in your breath. You walk and the walls ripple like a curtain of light. It is beautiful. It is also, per my instruments, one continuous sheet of something that was recently alive.",
+	"The Gilded Gullet narrows until you are single file between two walls of fused treasure. Crowns, blades, chalices, all melted into one throat of metal. I note the shapes trapped in it and choose not to itemize them for you.",
+	"You enter a vault where the gold has been laid over the walls like frosting, and underneath the frosting something is round, and regular, and arranged in rows. I count the rows. I stop counting the rows.",
+	"Warmth radiates up through the floor here, steady as a pilot light. Not the dead heat of Infernax behind you — this one has a pulse to it, slow and enormous. You are standing over something that is keeping itself warm.",
+	"The Clutch Vaults open into a chamber the size of a cathedral, and every surface drips with looted fortune. You could retire on one handful. I flag that the zone seems to want you to take a handful, which is exactly why I'd think twice.",
+	"Old torches still burn in the wall sconces down here, fed by nothing I can identify. The flame is the wrong color — older, if fire can be old. You pass them and they lean toward you like they recognize the taste.",
+	"The gilding thins as you descend, gold giving way to bare black rock scored with claw-marks the size of doorways. Something the size of a cathedral has been pacing this room, in tight circles, for a very long time. I file this under 'the guard dog was the small one.'",
+	"You reach the Cradle's threshold. The treasure ends abruptly, as if swept back, and the floor beyond is scorched smooth and warm and empty. Empty is the wrong word. I recommend you treat 'empty' as a placeholder for 'not yet.'",
+}
+
+// BOSS ENTRY
+var BossEntryAurvandryx = []string{
+	"The far wall is not a wall. It breathes, and when it breathes the whole cradle brightens, and an eye the size of a shield opens in the dark and finds you standing in her gold. Aurvandryx, the Ember Before Fire. Infernax was the puppy she left at the door.",
+	"She unfolds. That is the only verb I have — a mountain of ember and old scale sorting itself into a shape, and every scale on her is one she has shed a thousand times, and every dragon you have ever killed was one of those scales walking around. You did not raid a hoard. You woke a mother.",
+	"The clutch behind her is gilded because she gilded it herself, coin by coin, over an age, the way lesser things build a nest of leaves. You have been walking through her care all this time. Now the care turns around and looks at you. I recommend you look smaller than you feel.",
+	"'Ember Before Fire' is not a title. It is a job description. She predates the concept you are relying on — heat, flame, the whole idea — and she regards your fireproofing the way you'd regard a raincoat in the ocean. I file this under 'category error, ours.'",
+	"She takes stock of you slowly, and I watch her do arithmetic on everything you're carrying. Every coin in your pack, every gilded blade, gets weighed. I don't know what the sum buys, but I know it isn't discount. Travel light from here would have been the advice, if there were still a 'from here.'",
+}
+
+// LORE
+var LoreLinesFirstHoard = []string{
+	"Infernax was never the owner of this hoard. He was the guard dog, chained to the front door of a house whose true tenant sleeps four regions down. Killing him rang the bell. She heard the bell.",
+	"Every dragon in every story you have ever fought is a scale she shed and forgot. Red ones, the frost ones, the little arcade ones that spat three fireballs and died — offcuts. Dander. This is the animal they came off of.",
+	"The hoard is not treasure and was never treasure. It is a clutch — eggs — gilded over across an age until the gold is a shell and the shell is the point. The richer a vault looks, the more of them are under it.",
+	"There is an old vow carved at the lip of the Gullet, in a hand older than the coins: 'Come poor to the warm dark, and the warm dark forgets you are food.' I have no data on whether it works. I have a strong opinion about testing it.",
+	"The Coinborn are the hoard's antibodies. You are an infection — a warm thing that wants to take metal out of the nest — and the coins rise up person-shaped to give it back to you, edge first, in the shape of your own favorite weapon.",
+	"The cult that fed the Wyrm-Sworn their scales believed eating her leavings made them kin. It half works. The scale keeps them warm and keeps them loyal and keeps eating, and by the end there is more ember than man, and the ember answers to her.",
+	"The Choir Drake never had wings and never wanted them, because it never intended to leave the cradle. It stayed and it sang, one note held across centuries, and the note is load-bearing. When it stops singing, listen for what the song was holding up.",
+	"She is called the Ember Before Fire because she remembers the world before it caught. Your resistances, your wards, your fireproof cloaks — they are arguments with fire. She is older than the argument. I file this under 'bring a different plan.'",
+}
+
+// SIGNATURE COMBAT CALLOUTS
+var AurvandryxSignatureCallouts = []string{
+	"She inhales, and the light dims as she takes it in. 'First Flame incoming — that's the fire that predates fire resistance. Spread out and pray your ward has a sense of humor.'",
+	"Her jaw drops open on a furnace older than furnaces. 'First Flame. Whatever number your fire-resist reads, treat it as zero and move.'",
+	"A wing sweeps the cradle and a tide of loose coin comes with it. 'Gold wave — she's throwing the hoard at you. It's still your money and it still has an edge.'",
+	"She weighs you again mid-swing, and the richer you look the harder the tail lands. 'She's taxing the take. Everything shiny on you just made that hit bigger.'",
+	"The scales along her back lift and shed, and each one lands walking. 'She's dropping dragons like dandruff — clear the offcuts before they gang up.'",
+	"Her breath draws long and the color goes out of your torch. 'That's the deep breath. First Flame's cooking — commit to cover now, apologize later.'",
+	"She sets her claws and the whole cradle tilts toward her. 'She's pulling the room downhill — mind your footing, the gold's a landslide waiting for a cue.'",
+	"An eye the size of a shield tracks the fullest pack in the party. 'She's shopping. Whoever's carrying the most just got promoted to primary target.'",
+	"Her chest lights from the inside, ribs printed in ember. 'Core's glowing — that's the tell before First Flame. You have one beat. Use it.'",
+	"She hums, low, and the Choir's old note answers from the walls. 'Resonance building — the stone remembers the stun. Don't be against a wall when it lands.'",
+}
+
+// BOSS PHASE TWO
+var AurvandryxPhaseTwoLines = []string{
+	"Below forty percent she stops pretending she needs the scales. They slough off all at once and she stands there raw and first and burning, and I watch your fire resistance tick to zero on my readout and stay there. 'Phase two. The wards are decoration now. Kill her before she exhales.'",
+	"Under forty she breathes without winding up, because the tell was a courtesy and courtesy is over. First Flame on tap, no charge, no warning. 'She's done telegraphing — assume the fire is always about to happen and it usually is.'",
+	"At forty percent the Greed Tax comes due all at once. Every coin you pocketed on the way down, every gilded blade, she reads the ledger and bills you in one hit. 'This is the invoice. If you came in lean, you laugh at this. If you gilded yourself, I'm sorry.'",
+}