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.

packages/types/src/index.ts

@@ -22,6 +22,11 @@ export type {
   UpdateProfileResponse,
 } from "./interfaces/Api.js";
 export type { Boss, BossStatus } from "./interfaces/Boss.js";
+export type {
+  DailyChallenge,
+  DailyChallengeState,
+  DailyChallengeType,
+} from "./interfaces/DailyChallenge.js";
 export type {
   Equipment,
   EquipmentBonus,

packages/types/src/interfaces/DailyChallenge.ts

@@ -0,0 +1,17 @@
+export type DailyChallengeType = "clicks" | "bossesDefeated" | "questsCompleted" | "prestige";
+
+export interface DailyChallenge {
+  id: string;
+  type: DailyChallengeType;
+  label: string;
+  target: number;
+  progress: number;
+  completed: boolean;
+  rewardCrystals: number;
+}
+
+export interface DailyChallengeState {
+  /** ISO date string (e.g. "2026-03-06") used to detect when to reset */
+  date: string;
+  challenges: DailyChallenge[];
+}

packages/types/src/interfaces/GameState.ts

@@ -1,6 +1,7 @@
 import type { Achievement } from "./Achievement.js";
 import type { Adventurer } from "./Adventurer.js";
 import type { Boss } from "./Boss.js";
+import type { DailyChallengeState } from "./DailyChallenge.js";
 import type { Equipment } from "./Equipment.js";
 import type { Player } from "./Player.js";
 import type { PrestigeData } from "./Prestige.js";
@@ -24,4 +25,6 @@ export interface GameState {
   baseClickPower: number;
   /** Unix timestamp of the last client-side tick */
   lastTickAt: number;
+  /** Daily challenge progress — optional for backwards compatibility with old saves */
+  dailyChallenges?: DailyChallengeState;
 }