fix: add runId to seed calculations and use seeded random for treasure loot

Fixes #299: Seed calculation now includes runId component per spec (seed = floor × 12345 + runId)
Fixes #298: Treasure loot now uses seeded random instead of Math.random()

Changes:
- Added runId field to CombatState type
- Generated random runId on spire entry in createEnterSpireMode
- Updated getRoomsForFloor, generateSpireRoomType, generateSpireFloorState, generateTreasureLoot to accept and use runId
- Updated all call sites in combat-descent-actions.ts and combatStore.ts
- Treasure loot item count now uses seeded RNG instead of Math.random()

src/lib/game/utils/spire-utils.ts

@@ -39,15 +39,13 @@ function makeSeededRandom(seed: number): () => number {
 // Deterministic per floor via seed = floor × 12345 + runId.
 // Guardian floors always return 1.
 
-export function getRoomsForFloor(floor: number, seed?: number): number {
+export function getRoomsForFloor(floor: number, seed: number): number {
   if (isGuardianFloor(floor)) return 1;
   const base = 5;
   const floorBonus = Math.min(10, Math.floor(floor / 20));
 
-  // Use seeded random if a seed is provided, otherwise fall back to Math.random
-  const randomVariation = seed !== undefined
-    ? Math.floor(makeSeededRandom(seed)() * 3)
-    : Math.floor(Math.random() * 3);
+  // Use seeded random; seed should be floor × 12345 + runId per spec
+  const randomVariation = Math.floor(makeSeededRandom(seed)() * 3);
 
   return base + floorBonus + randomVariation;
 }
@@ -62,6 +60,7 @@ export function generateSpireRoomType(
   floor: number,
   roomIndex: number,
   totalRooms: number,
+  runId: number = 0,
 ): SpireRoomType {
   // Last room on guardian floors is always guardian
   if (isGuardianFloor(floor) && roomIndex === totalRooms - 1) {
@@ -70,18 +69,18 @@ export function generateSpireRoomType(
 
   // Override: every 7th floor, one room (chosen by seed) is always 'puzzle'
   if (floor % 7 === 0) {
-    const puzzleIndex = Math.floor(makeSeededRandom(floor * 12345 + 7)() * totalRooms);
+    const puzzleIndex = Math.floor(makeSeededRandom(floor * 12345 + runId + 7)() * totalRooms);
     if (roomIndex === puzzleIndex) {
       return 'puzzle';
     }
   }
 
-  // Base roll
-  const roll = makeSeededRandom(floor * 1000 + roomIndex)();
+  // Base roll — seed includes runId for per-run variety
+  const roll = makeSeededRandom(floor * 1000 + roomIndex + runId)();
 
   if (roll < 0.10) {
     // Rare roll — secondary roll determines sub-type
-    const rareRoll = makeSeededRandom(floor * 1000 + roomIndex + 9999)();
+    const rareRoll = makeSeededRandom(floor * 1000 + roomIndex + runId + 9999)();
     if (rareRoll < 0.40) return 'recovery';
     if (rareRoll < 0.70) return 'treasure';
     return 'library';
@@ -93,8 +92,8 @@ export function generateSpireRoomType(
 
 // ─── Floor State Generation ───────────────────────────────────────────────────
 
-export function generateSpireFloorState(floor: number, roomIndex: number, totalRooms: number): FloorState {
-  const roomType = generateSpireRoomType(floor, roomIndex, totalRooms);
+export function generateSpireFloorState(floor: number, roomIndex: number, totalRooms: number, runId: number = 0): FloorState {
+  const roomType = generateSpireRoomType(floor, roomIndex, totalRooms, runId);
   const element = getFloorElement(floor);
   const baseHP = getFloorMaxHP(floor);
 
@@ -131,7 +130,7 @@ export function generateSpireFloorState(floor: number, roomIndex: number, totalR
     case 'puzzle': {
       const puzzleKeys = Object.keys(PUZZLE_ROOMS);
       const puzzleIdx = Math.floor(
-        makeSeededRandom(floor * 1000 + roomIndex + 5000)() * puzzleKeys.length,
+        makeSeededRandom(floor * 1000 + roomIndex + runId + 5000)() * puzzleKeys.length,
       );
       const selectedPuzzle = puzzleKeys[puzzleIdx];
       const puzzle = PUZZLE_ROOMS[selectedPuzzle];
@@ -162,7 +161,7 @@ export function generateSpireFloorState(floor: number, roomIndex: number, totalR
       };
 
     case 'treasure': {
-      const loot = generateTreasureLoot(floor);
+      const loot = generateTreasureLoot(floor, runId);
       return {
         roomType: 'treasure',
         enemies: [],
@@ -279,18 +278,21 @@ export function calcInsight(floor: number, isGuardian: boolean): number {
  * Generate treasure loot for a treasure room based on floor.
  * Returns pre-generated loot drops that are progressively revealed.
  */
-export function generateTreasureLoot(floor: number): LootDrop[] {
+export function generateTreasureLoot(floor: number, runId: number = 0): LootDrop[] {
   const available = getAvailableDrops(floor, false);
   const drops: LootDrop[] = [];
 
+  // Use seeded random for deterministic loot
+  const rng = makeSeededRandom(floor * 12345 + runId + 31337);
+
   // Determine item count based on floor
   let itemCount: number;
   if (floor <= 10) {
-    itemCount = 2 + Math.floor(Math.random() * 2); // 2-3
+    itemCount = 2 + Math.floor(rng() * 2); // 2-3
   } else if (floor <= 50) {
-    itemCount = 4 + Math.floor(Math.random() * 4); // 4-7
+    itemCount = 4 + Math.floor(rng() * 4); // 4-7
   } else {
-    itemCount = 8 + Math.floor(Math.random() * 8); // 8-15
+    itemCount = 8 + Math.floor(rng() * 8); // 8-15
   }
 
   // Roll for each item