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_turn_engine.go

@@ -363,6 +363,8 @@ func resumeTurnEngine(sess *CombatSession, players []*Combatant, enemy *Combatan
 		enemyRetaliateFrac: sess.Statuses.EnemyRetaliateFrac,
 		enemyRegen:         sess.Statuses.EnemyRegen,
 		enemySurviveArmed:  sess.Statuses.EnemySurviveArmed,
+		enemyReviveCharges: sess.Statuses.EnemyReviveCharges,
+		enemyReviveHP:      sess.Statuses.EnemyReviveHP,
 		// Slice-4 monster-ability effects — the former flavor-only placeholders.
 		enemySpellResist: sess.Statuses.EnemySpellResist,
 		enemyRevealNext:  sess.Statuses.EnemyRevealNext,
@@ -926,6 +928,8 @@ func (te *turnEngine) commit() {
 	s.EnemyRetaliateFrac = st.enemyRetaliateFrac
 	s.EnemyRegen = st.enemyRegen
 	s.EnemySurviveArmed = st.enemySurviveArmed
+	s.EnemyReviveCharges = st.enemyReviveCharges
+	s.EnemyReviveHP = st.enemyReviveHP
 	s.EnemySpellResist = st.enemySpellResist
 	s.EnemyRevealNext = st.enemyRevealNext
 	s.EnemyFearImmune = st.enemyFearImmune