feat: game state, persistence, UI framework (Alpine+Tailwind), economy system (#10, #11, #12)

- Game state with localStorage save/load + reset (type DELETE to confirm)
- Alpine.js + Tailwind CSS + Lucide UI overlay (HUD bar, shop modal, settings, toasts)
- Economy: fish prices, tank tier costs/capacities, rarity multipliers, sell value formula
- Genetic system: hue/saturation/size/speed/pattern/rarity/gender + breeding inheritance
- Fish selection via raycaster (click fish = select, click empty = drop food)
- Buy/Sell/Breed/Upgrade actions wired to game state

src/types/alpinejs.d.ts

@@ -0,0 +1,15 @@
+declare module "alpinejs" {
+  interface AlpineData {
+    data(key: string, value: () => any): void;
+    store(name: string, value: Record<string, any>): void;
+    start(): void;
+    addDirective(name: string, handler: (...args: any[]) => void): void;
+    magic(name: string, handler: (...args: any[]) => any): void;
+  }
+  const Alpine: AlpineData & {
+    data: (key: string, value: () => any) => void;
+    store: (name: string, value: Record<string, any>) => void;
+    start: () => void;
+  };
+  export default Alpine;
+}