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/plugin/dnd_zone_narration.go

@@ -92,6 +92,16 @@ func zoneRoomEntryPool(zoneID ZoneID) []string {
 		return append(append([]string{}, flavor.RoomEntryDragonsLair...), flavor.RoomEntryGeneric...)
 	case ZoneAbyssPortal:
 		return append(append([]string{}, flavor.RoomEntryAbyssPortal...), flavor.RoomEntryGeneric...)
+	case ZoneOssuaryAscendant:
+		return append(append([]string{}, flavor.RoomEntryOssuaryAscendant...), flavor.RoomEntryGeneric...)
+	case ZoneFirstHoard:
+		return append(append([]string{}, flavor.RoomEntryFirstHoard...), flavor.RoomEntryGeneric...)
+	case ZoneUnplace:
+		return append(append([]string{}, flavor.RoomEntryUnplace...), flavor.RoomEntryGeneric...)
+	case ZoneDrownedStar:
+		return append(append([]string{}, flavor.RoomEntryDrownedStar...), flavor.RoomEntryGeneric...)
+	case ZoneLastMeridian:
+		return append(append([]string{}, flavor.RoomEntryLastMeridian...), flavor.RoomEntryGeneric...)
 	}
 	return flavor.RoomEntryGeneric
 }
@@ -120,6 +130,16 @@ func bossEntryPool(zoneID ZoneID) []string {
 		return flavor.BossEntryInfernax
 	case ZoneAbyssPortal:
 		return flavor.BossEntryBelaxath
+	case ZoneOssuaryAscendant:
+		return flavor.BossEntryValdrisAscendant
+	case ZoneFirstHoard:
+		return flavor.BossEntryAurvandryx
+	case ZoneUnplace:
+		return flavor.BossEntrySeamstress
+	case ZoneDrownedStar:
+		return flavor.BossEntrySeraphel
+	case ZoneLastMeridian:
+		return flavor.BossEntryCustodian
 	}
 	return flavor.BossEntryGeneric
 }
@@ -182,6 +202,16 @@ func zoneLorePool(zoneID ZoneID) []string {
 		return append(append([]string{}, flavor.LoreLinesDragonsLair...), flavor.LoreLines...)
 	case ZoneAbyssPortal:
 		return append(append([]string{}, flavor.LoreLinesAbyssPortal...), flavor.LoreLines...)
+	case ZoneOssuaryAscendant:
+		return append(append([]string{}, flavor.LoreLinesOssuaryAscendant...), flavor.LoreLines...)
+	case ZoneFirstHoard:
+		return append(append([]string{}, flavor.LoreLinesFirstHoard...), flavor.LoreLines...)
+	case ZoneUnplace:
+		return append(append([]string{}, flavor.LoreLinesUnplace...), flavor.LoreLines...)
+	case ZoneDrownedStar:
+		return append(append([]string{}, flavor.LoreLinesDrownedStar...), flavor.LoreLines...)
+	case ZoneLastMeridian:
+		return append(append([]string{}, flavor.LoreLinesLastMeridian...), flavor.LoreLines...)
 	}
 	return flavor.LoreLines
 }
@@ -211,6 +241,16 @@ func bossSignaturePool(zoneID ZoneID) []string {
 		return flavor.InfernaxSignatureCallouts
 	case ZoneAbyssPortal:
 		return flavor.BelaxathSignatureCallouts
+	case ZoneOssuaryAscendant:
+		return flavor.ValdrisAscendantSignatureCallouts
+	case ZoneFirstHoard:
+		return flavor.AurvandryxSignatureCallouts
+	case ZoneUnplace:
+		return flavor.SeamstressSignatureCallouts
+	case ZoneDrownedStar:
+		return flavor.SeraphelSignatureCallouts
+	case ZoneLastMeridian:
+		return flavor.CustodianSignatureCallouts
 	}
 	return nil
 }
@@ -236,6 +276,16 @@ func bossPhaseTwoPool(zoneID ZoneID) []string {
 		return flavor.InfernaxPhaseTwoLines
 	case ZoneAbyssPortal:
 		return flavor.BelaxathPhaseTwoLines
+	case ZoneOssuaryAscendant:
+		return flavor.ValdrisAscendantPhaseTwoLines
+	case ZoneFirstHoard:
+		return flavor.AurvandryxPhaseTwoLines
+	case ZoneUnplace:
+		return flavor.SeamstressPhaseTwoLines
+	case ZoneDrownedStar:
+		return flavor.SeraphelPhaseTwoLines
+	case ZoneLastMeridian:
+		return flavor.CustodianPhaseTwoLines
 	}
 	return nil
 }