feat: implement DoT/debuff runtime system (spec §6, AC-12, AC-13)

- Add ActiveEffect, EffectType types to game.ts; activeEffects + effectiveArmor on EnemyState
- Add SpellOnHitEffect + onHitEffect field to SpellDefinition
- Wire onHitEffect to fire (burn), death (curse), lightning (armor_corrode), frost (freeze), soul (bypassArmor burn)
- Add applyOnHitEffect() — applies on-hit effect on successful spell hit (spec §6.2)
- Add processDoTPhase() — ticks all active effects after weapon/golem attacks (spec §6.3)
- Add bypassArmor/bypassBarrier support in applyEnemyDefenses() (AC-13)
- Export standalone applyEnemyDefenses from combat-tick.ts for DoT pipeline
- Split DoT runtime into separate dot-runtime.ts (135 lines) to keep combat-actions.ts under 400 lines
- Update all enemy generation sites with activeEffects/effectiveArmor defaults
- Fix test helpers for new required fields

All 921 tests pass (45 test files)

docs/project-structure.txt

@@ -12,6 +12,21 @@ Mana-Loop/
 │   └── pre-commit
 ├── docs/
 │   ├── specs/
+│   │   ├── attunements/
+│   │   │   ├── enchanter/
+│   │   │   │   ├── systems/
+│   │   │   │   │   └── enchanting-spec.md
+│   │   │   │   └── enchanter-spec.md
+│   │   │   ├── fabricator/
+│   │   │   │   ├── systems/
+│   │   │   │   │   ├── golemancy-spec.md
+│   │   │   │   │   └── item-fabrication-spec.md
+│   │   │   │   └── fabricator-spec.md
+│   │   │   ├── invoker/
+│   │   │   │   ├── systems/
+│   │   │   │   │   └── pact-system-spec.md
+│   │   │   │   └── invoker-spec.md
+│   │   │   └── attunement-system-spec.md
 │   │   ├── spire-climbing-spec.md
 │   │   └── spire-combat-spec.md
 │   ├── GAME_BRIEFING.md
@@ -347,6 +362,7 @@ Mana-Loop/
 │   │   │   │   ├── craftingStore.types.ts
 │   │   │   │   ├── debugBridge.ts
 │   │   │   │   ├── discipline-slice.ts
+│   │   │   │   ├── dot-runtime.ts
 │   │   │   │   ├── gameActions.ts
 │   │   │   │   ├── gameHooks.ts
 │   │   │   │   ├── gameLoopActions.ts