N2/B1+B4+C4: tempering, the expedition achievement wing, arena seasons

B1 — tempering. `!adventure temper` pushes an owned magic item one rung up
the rarity ladder at the blacksmith, capped at Legendary. Rarity lives on
the registry definition, so an upgraded instance records its progress as a
`temper` step count on its own row (adventure_inventory, magic_item_equipped)
and effective rarity is derived on read. The stored base rarity is never
written back, so an item cannot double-bump across a load/save round-trip.
Effects flow through the existing rarity scalars — no new combat math, and
the Legendary cap means this accelerates reaching the current ceiling rather
than raising it.

Costs mirror the crafting ladder (10k/25k/60k/150k, Foraging 15/20/25/30).
Only the Legendary rung consumes a T5 material; gating the lower rungs on
one would make tempering unreachable until a player already clears T5.

Two plan anchors were wrong: thyraks_core and portal_fragment are not
loot-note strings needing promotion — they are UniqueAlways slate entries
that already materialize as inventory rows on every T5 clear.

B4 — expedition achievement wing: first-clear and all-zones-cleared per tier
(10), a quiet-clear for keeping peak threat under 50, and temper_legendary.
The quiet-clear requires max_threat_seen to be *present*, not merely low:
recordMaxThreat samples only on day rollover and never stores a zero, so an
absent key means no threat history, not low threat. The plan's no-death-T4
achievement is not shipped — no per-expedition death counter exists — and
pet-saved-my-life already ships as combat_pet_save.

C4 — arena seasons. Standings are derived from arena_history.created_at per
calendar quarter rather than wiping arena_stats: same visible reset, but
lifetime totals survive for `!arena stats` and no destructive job can fire
twice. Crowns archive to arena_season_titles rather than player_meta.title,
which already carries the Survivalist milestone. Rollover rides the existing
midnight ticker and self-dedups on the season key, so a bot that was down on
the boundary catches up on its next wake.

internal/plugin/adventure_flavor_blacksmith.go

@@ -49,6 +49,22 @@ var blacksmithArena = []string{
 	"The Arena gear gets the good tools. I don't use these for everything. Just for things that matter.",
 }
 
+var blacksmithTemperGreetings = []string{
+	"_sets aside the repair work_ You want me to make something _more_ than it is. That's different. That's the good work.",
+	"Tempering. _rolls his shoulders_ I don't repair it. I take it apart and I convince it to come back stronger. It doesn't always want to.",
+	"_wipes the counter clean with one sweep_ Put it down. Right there. Let me see what it could be instead of what it is.",
+	"Anything can be pushed further. Anything. It's just a question of what you're willing to spend and how much heat it can take before it gives in.",
+	"_eyes light up_ Oh, you've come for the real thing. Not a patch. A _change_. Show me. Show me everything you've got.",
+}
+
+var blacksmithTemperCompletion = []string{
+	"_lifts it from the quench, steam everywhere_ Feel the weight of it now. It's not the same thing you handed me. It never will be again.",
+	"_breathing hard_ It fought me. Right to the end it fought me. And now look at it. Look what it became.",
+	"There. _sets it down with enormous care_ I pushed it further than it wanted to go, and it thanked me for it. They always do.",
+	"_holds it up, turning it slowly_ I've been doing this a long time and this one still surprised me. Take it before I change my mind about giving it back.",
+	"It's still hot. It'll be hot for a while. That's what happens when you ask something to become more than it was.",
+}
+
 var blacksmithFullCondition = []string{
 	"_looks it over_ There's nothing to do here. It doesn't need me. _sounds slightly disappointed_ Come back when it does.",
 	"Full condition. You've been taking care of it. Good. I appreciate that in a person.",