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/stores/combat-descent-actions.ts

@@ -7,6 +7,8 @@ import { generateSpireFloorState, getRoomsForFloor } from '../utils/spire-utils'
 import { getGuardianForFloor } from '../data/guardian-encounters';
 import { usePrestigeStore } from './prestigeStore';
 import { useDisciplineStore } from './discipline-slice';
+import { useManaStore } from './manaStore';
+import { summonGolemsOnRoomEntry } from './golem-combat-actions';
 import type { FloorState } from '../types';
 
 type GetFn = () => CombatStore;
@@ -78,6 +80,9 @@ export function advanceRoomOrFloor(get: GetFn, set: SetFn): void {
       });
     }
 
+    // ── Golem summoning on room entry (spec §9.3) ─────────────────────
+    summonGolemsForRoom(get, set);
+
     onEnterRoomDescend(get, set);
   } else {
     // ── Ascending (spec §4.4) ─────────────────────────────────────────────
@@ -116,6 +121,9 @@ export function advanceRoomOrFloor(get: GetFn, set: SetFn): void {
       });
     }
 
+    // ── Golem summoning on room entry (spec §9.3) ─────────────────────
+    summonGolemsForRoom(get, set);
+
     // Handle non-combat rooms on ascent
     const room = get().currentRoom;
     if (room.roomType === 'library') {
@@ -126,6 +134,39 @@ export function advanceRoomOrFloor(get: GetFn, set: SetFn): void {
   }
 }
 
+// ─── Golem Summoning on Room Entry (spec §9.3) ──────────────────────────────
+
+function summonGolemsForRoom(get: GetFn, set: SetFn): void {
+  const s = get();
+  const manaState = useManaStore.getState();
+  const enabledGolems = s.golemancy?.enabledGolems ?? [];
+  if (enabledGolems.length === 0) return;
+
+  const currentActiveGolems = s.golemancy?.activeGolems ?? [];
+  const summonResult = summonGolemsOnRoomEntry(
+    enabledGolems,
+    manaState.rawMana,
+    manaState.elements,
+    s.currentFloor,
+    currentActiveGolems,
+  );
+
+  if (summonResult.logMessages.length > 0) {
+    summonResult.logMessages.forEach((msg) => get().addActivityLog('special_effect', msg));
+  }
+
+  // Write summoned golems back to combat store
+  set({
+    golemancy: { ...s.golemancy, activeGolems: summonResult.activeGolems },
+  });
+
+  // Deduct summon costs from mana store
+  useManaStore.setState({
+    rawMana: summonResult.rawMana,
+    elements: summonResult.elements,
+  });
+}
+
 // ─── onEnterRoomDescend (climbing spec §4.7) ──────────────────────────────────
 
 export function onEnterRoomDescend(get: GetFn, set: SetFn): void {
@@ -240,6 +281,7 @@ export function createEnterSpireMode(get: GetFn, set: SetFn, generateFloorState:
       roomResetState: {},
       descentPeak: null,
       isDescentComplete: false,
+      golemancy: { enabledGolems: [], summonedGolems: [], activeGolems: [], lastSummonFloor: 0 },
     });
 
     get().addActivityLog('floor_transition',