feat: add daily challenges system

Three PST-midnight-resetting challenges generated deterministically per
day from click, boss, quest, and prestige types. Progress tracked
server-side for bosses and prestige, client-side for clicks and quests.
Crystal rewards awarded on completion and preserved through prestige resets.

apps/api/src/routes/boss.ts

@@ -2,6 +2,7 @@ import type { BossChallengeResponse, GameState } from "@elysium/types";
 import { Hono } from "hono";
 import { prisma } from "../db/client.js";
 import { authMiddleware } from "../middleware/auth.js";
+import { updateChallengeProgress } from "../services/dailyChallenges.js";
 
 export const bossRouter = new Hono();
 
@@ -173,6 +174,17 @@ bossRouter.post("/challenge", async (context) => {
       }
     }
 
+    // Update daily boss challenge progress
+    if (state.dailyChallenges) {
+      const { updatedChallenges, crystalsAwarded } = updateChallengeProgress(
+        state.dailyChallenges,
+        "bossesDefeated",
+        1,
+      );
+      state.dailyChallenges = updatedChallenges;
+      state.resources.crystals += crystalsAwarded;
+    }
+
     rewards = {
       gold: boss.goldReward,
       essence: boss.essenceReward,

apps/api/src/routes/game.ts

@@ -6,6 +6,7 @@ import { DEFAULT_ACHIEVEMENTS } from "../data/achievements.js";
 import { DEFAULT_ADVENTURERS } from "../data/adventurers.js";
 import { DEFAULT_EQUIPMENT } from "../data/equipment.js";
 import { authMiddleware } from "../middleware/auth.js";
+import { getOrResetDailyChallenges } from "../services/dailyChallenges.js";
 import { calculateOfflineEarnings } from "../services/offlineProgress.js";
 
 const RESOURCE_CAP = 1e300;
@@ -327,6 +328,9 @@ gameRouter.get("/load", async (context) => {
     state.resources.essence += offlineEssence;
   }
 
+  // Generate or reset daily challenges if a new day has begun
+  state.dailyChallenges = getOrResetDailyChallenges(state);
+
   state.lastTickAt = now;
 
   if (needsBackfill || offlineGold > 0 || offlineEssence > 0) {

apps/api/src/routes/prestige.ts

@@ -3,6 +3,7 @@ import { Hono } from "hono";
 import { prisma } from "../db/client.js";
 import { authMiddleware } from "../middleware/auth.js";
 import { DEFAULT_PRESTIGE_UPGRADES } from "../data/prestigeUpgrades.js";
+import { updateChallengeProgress } from "../services/dailyChallenges.js";
 import {
   buildPostPrestigeState,
   computeRunestoneMultipliers,
@@ -37,15 +38,34 @@ prestigeRouter.post("/", async (context) => {
     );
   }
 
+  // Update daily prestige challenge progress before resetting the run
+  let updatedDailyChallenges = state.dailyChallenges;
+  let challengeCrystals = 0;
+  if (updatedDailyChallenges) {
+    const result = updateChallengeProgress(updatedDailyChallenges, "prestige", 1);
+    updatedDailyChallenges = result.updatedChallenges;
+    challengeCrystals = result.crystalsAwarded;
+  }
+
   const { newState, newPrestigeData, runestonesEarned } = buildPostPrestigeState(
     state,
     characterName,
   );
 
+  // Preserve daily challenges across the prestige reset and apply any crystal rewards
+  const finalState: GameState = {
+    ...newState,
+    dailyChallenges: updatedDailyChallenges,
+    resources: {
+      ...newState.resources,
+      crystals: newState.resources.crystals + challengeCrystals,
+    },
+  };
+
   const now = Date.now();
   await prisma.gameState.update({
     where: { discordId },
-    data: { state: newState as object, updatedAt: now },
+    data: { state: finalState as object, updatedAt: now },
   });
 
   await prisma.player.update({