feat(sasch40): major overhaul with doodle jump, party bunker, and guitar hero

- Add global settings & pause modal (gear icon) with mute and reset, removing obsolete bag button
- Extend Prologue with Flo Maier (castle fire game over & Löschzug restart) and Viktor (vampire bite game over & Knoblauch restart)
- Rebuild Akt II as 3-level vertical Doodle Jump climber to rescue sisters Saskia, Maja, and Miriam with custom pixel portraits
- Update Akt III Schankraum with seamless oak floor, double-tap 'Luke zum Party Bunker', duel intro modals, and Hansi's departure in Hinterland
- Rebuild Akt IV as 3-lane medieval Guitar Hero rock concert with live crowd meter, combo multipliers, and Hansi duo
- Update AGENTS.md architectural documentation and playtest test suite

projects/sasch40/frontend/src/stores/gameStore.ts

@@ -15,6 +15,7 @@ export interface GameState {
   startTime: number
   elapsedSeconds: number
   soundMuted: boolean
+  isPaused: boolean
 }
 
 export const STORAGE_KEY = 'sasch40_game_save_v1'
@@ -34,6 +35,7 @@ function getInitialState(): GameState {
     startTime: Date.now(),
     elapsedSeconds: 0,
     soundMuted: false,
+    isPaused: false,
   }
 
   if (typeof window === 'undefined' || !window.localStorage) {
@@ -56,7 +58,8 @@ function getInitialState(): GameState {
         unlockedEasterEggs: Array.isArray(parsed.unlockedEasterEggs) ? parsed.unlockedEasterEggs : [],
         startTime: typeof parsed.startTime === 'number' ? parsed.startTime : defaults.startTime,
         elapsedSeconds: typeof parsed.elapsedSeconds === 'number' ? parsed.elapsedSeconds : 0,
-        soundMuted: Boolean(parsed.soundMuted)
+        soundMuted: Boolean(parsed.soundMuted),
+        isPaused: false
       }
       if (state.soundMuted) {
         sound.setMuted(true)
@@ -197,6 +200,14 @@ export const useGameStore = defineStore('game', {
       this.soundMuted = sound.toggleMute()
     },
 
+    pauseGame() {
+      this.isPaused = true
+    },
+
+    resumeGame() {
+      this.isPaused = false
+    },
+
     resetGame() {
       if (typeof window !== 'undefined' && window.localStorage) {
         try {