feat: implement golemancy combat system (spec §6, §9)

- Add ActiveGolem interface and activeGolems to GolemancyState
- Add maxRoomDuration to all 12 golem definitions
- Create golem-combat-actions.ts with pure golem combat logic (summoning, maintenance, attacks, room-duration)
- Create golem-combat.ts pipeline for golem combat setup
- Wire golem maintenance and attacks into processCombatTick
- Wire golem summoning into advanceRoomOrFloor on room entry
- Wire golem room-duration countdown into onFloorCleared callback
- Update combat-actions tests for new processCombatTick signature
- All 921 tests pass, all files under 400-line limit

Closes #259

src/lib/game/__tests__/tick-integration.test.ts

@@ -46,7 +46,7 @@ function resetAllStores() {
     clearedFloors: {},
     climbDirection: null,
     isDescending: false,
-    golemancy: { enabledGolems: [], summonedGolems: [], lastSummonFloor: 0 },
+    golemancy: { enabledGolems: [], summonedGolems: [], activeGolems: [], lastSummonFloor: 0 },
     equipmentSpellStates: [],
     comboHitCount: 0,
     floorHitCount: 0,