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>

package.json

@@ -0,0 +1,25 @@
+{
+  "name": "p1---kino",
+  "version": "1.0.0",
+  "description": "",
+  "main": "main.js",
+  "scripts": {
+    "build": "tsc",
+    "watch": "tsc --watch",
+    "serve": "serve .",
+    "run": "npm-run-all --parallel watch serve"
+  },
+  "repository": {
+    "type": "git",
+    "url": "ssh://git@gitea.starfour.de:2222/Aaron/Kino-Website.git"
+  },
+  "keywords": [],
+  "author": "Aaron und Jannis",
+  "license": "ISC",
+  "type": "commonjs",
+  "devDependencies": {
+    "npm-run-all": "^4.1.5",
+    "serve": "^14.2.6",
+    "typescript": "^6.0.3"
+  }
+}