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/pipelines/golem-combat.ts

@@ -0,0 +1,50 @@
+// ─── Golem Combat Pipeline ─────────────────────────────────────────────────────
+// Extracts golem combat setup from gameStore.ts tick()
+// to keep the coordinator under the 400-line file limit.
+
+import { useCombatStore } from '../combatStore';
+import { useManaStore } from '../manaStore';
+import { processGolemRoomDuration } from '../golem-combat-actions';
+import type { ActiveGolem } from '../../types';
+
+export interface GolemCombatContext {
+  addLog: (msg: string) => void;
+  ctx: {
+    combat: {
+      currentFloor: number;
+      currentRoom: { roomType: string; unknown: Array<{ name: string }> };
+    };
+    prestige: { signedPacts: number[] };
+  };
+  rawMana: number;
+  elements: Record<string, { current: number; max: number; unlocked: boolean }>;
+  maxMana: number;
+}
+
+export interface GolemCombatResult {
+  rawMana: number;
+  elements: Record<string, { current: number; max: number; unlocked: boolean }>;
+}
+
+/**
+ * Build the golem combat pipeline for the current tick.
+ * Returns golem state needed by processCombatTick.
+ */
+export function buildGolemCombatPipeline(_addLog: (msg: string) => void): {
+  activeGolems: ActiveGolem[];
+  golemApplyDamageToRoom: (dmg: number) => { floorHP: number; floorMaxHP: number; roomCleared: boolean };
+} {
+  const activeGolems = useCombatStore.getState().golemancy?.activeGolems ?? [];
+
+  const golemApplyDamageToRoom = (dmg: number) => {
+    const cs = useCombatStore.getState();
+    if (dmg > 0) {
+      const newFloorHP = Math.max(0, cs.floorHP - dmg);
+      useCombatStore.setState({ floorHP: newFloorHP });
+    }
+    const roomCleared = useCombatStore.getState().floorHP <= 0;
+    return { floorHP: cs.floorHP, floorMaxHP: cs.floorMaxHP, roomCleared };
+  };
+
+  return { activeGolems, golemApplyDamageToRoom };
+}