adventure: T6 Phylactery Verses + stackable-rebirth engine primitive (P8)

The second Layer-2 postgame boss mechanic, and the first stateful in-combat one.
Valdris ("boss_valdris_ascendant", the Ossuary Ascendant) is bound to three
Verses hidden on the zone's secret nodes: every Verse the player finds and walks
before the fight unbinds one rebirth, every Verse they skip leaves it armed. A
full-clear explorer strips all three and fights a mortal lich; a speedrunner who
blows past the secrets fights a god who will not stay down.

New engine primitive: stackable rebirth. The stock survive_at_1 is a one-shot
1-HP stay; Valdris needs several rebirths that each restore a real pool.
combatState/CombatStatuses gain EnemyReviveCharges/EnemyReviveHP (round-tripped
through the turn engine so a suspend/resume keeps the live count), and enemyDown
consumes a charge after the survive_at_1 check, reviving to 25% of the
party-scaled max and emitting a phylactery_rebirth event. Zero for every
non-Valdris fight.

Unlike Greed Tax (a pure per-round recompute in applyBossRunModifiers), rebirths
are spent mid-fight, so the charge count is seeded ONCE at session creation
(seedBossRunStatuses, from unvisited secret Verses) and never re-derived on the
per-round enemy rebuild. Seeded from handleFightCmd after startPartyCombatSession.

Sim A/B (millenia, n=120 L20 party+Pete+pets, same binary, control neuters the
dispatch): mortal end (verses found) fighter 42.5% -- reproduces the deployed P7
ossuary baseline, confirming the mechanic doesn't touch the validated full-clear
path -- and the god end (0 verses) fighter 12.5%, a deadly-but-beatable flex arm.
The sim walks 0 verses (autopilot takes the first unlocked fork; Verses are
behind Perception locks), so the A/B brackets the whole player-agency gradient.

Claude-Session: https://claude.ai/code/session_0156WqjgsbmSY2U8eQ3Kkb1s

internal/plugin/combat_session.go

@@ -215,6 +215,17 @@ type CombatStatuses struct {
 	EnemyRegen         int     `json:"enemy_regen,omitempty"`
 	EnemySurviveArmed  bool    `json:"enemy_survive_armed,omitempty"`
 
+	// Phylactery Verses (Tier-6 postgame, Valdris Ascendant). Unlike the
+	// proc-armed EnemySurviveArmed one-shot, this is a *count* of rebirths seeded
+	// once at fight start (seedBossRunStatuses) from how many of the zone's secret
+	// Verses the player left un-found. Each consumed rebirth (enemyDown) revives
+	// the boss to EnemyReviveHP. Both fields are frozen at seed time except
+	// EnemyReviveCharges, which decrements as rebirths are spent — so they must
+	// round-trip through combatState to survive a suspend/resume. Zero for every
+	// other enemy, so omitempty keeps them off every non-Valdris row.
+	EnemyReviveCharges int `json:"enemy_revive_charges,omitempty"`
+	EnemyReviveHP      int `json:"enemy_revive_hp,omitempty"`
+
 	// Slice-4 monster-ability effects — the former flavor-only placeholders.
 	// EnemyRevealNext is a one-shot; the other three persist for the fight.
 	EnemySpellResist bool `json:"enemy_spell_resist,omitempty"`