fix: console errors - null crash, 404s und fehlende Bilder

- account.ts: null-Guard vor normalizeUser() wenn kein User im LocalStorage
- index.html: plain-JS Dateien (cart, booking, checkout, main) von dist/ auf src/ umgestellt
- index.html: dolby.png -> Dolby.png und dbox.png -> dbox.jpg (falsche Dateinamen)
- style.css: placeholder-Bilder auf vorhandene Dateien umgestellt (shelter.jpg, dbox.jpg, popcorn.jpg)
- Projekt-Setup (package.json, tsconfig.json, src/) initial commitet

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,45 @@
+{
+  // Visit https://aka.ms/tsconfig to read more about this file
+  "compilerOptions": {
+    // File Layout
+    "rootDir": "./src",
+    "outDir": "./dist",
+
+    // Environment Settings
+    // See also https://aka.ms/tsconfig/module
+    "module": "ES2020",
+    "target": "ES2021",
+    "types": [],
+    // For nodejs:
+    // "lib": ["esnext"],
+    // "types": ["node"],
+    // and npm install -D @types/node
+
+    // Other Outputs
+    "sourceMap": true,
+    "declaration": true,
+    "declarationMap": true,
+
+    // Stricter Typechecking Options
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+
+    // Style Options
+    // "noImplicitReturns": true,
+    // "noImplicitOverride": true,
+    // "noUnusedLocals": true,
+    // "noUnusedParameters": true,
+    // "noFallthroughCasesInSwitch": true,
+    // "noPropertyAccessFromIndexSignature": true,
+
+    // Recommended Options
+    "strict": true,
+    "jsx": "react-jsx",
+    "verbatimModuleSyntax": true,
+    "isolatedModules": true,
+    "noUncheckedSideEffectImports": true,
+    "moduleDetection": "force",
+    "skipLibCheck": true,
+  },
+  "include": ["src/*"]
+}