Add Playwright E2E testing with recorded workflows

- Add @playwright/test as dev dependency
- Create playwright.config.ts with Chrome-only testing config
- Add npm scripts: test:record, test:e2e, test:replay
- Create 13 test recordings covering:
  - 2-player and 3-player games
  - 8-ball, 9-ball, and 10-ball game types
  - Various race-to values (1, 3, 5, 7, 9) and "endlos" mode
  - Both wechselbreak (alternating) and winnerbreak rules
- Fix Infinity handling in gameService.ts and NewGameScreen.tsx
  - Parse "endlos" and "Infinity" strings as Infinity number
  - Properly serialize Infinity as string in form data
- Increase GameDetail score font size from 20vh to 40vh
- Update README.md with testing documentation:
  - Quick start guide for recording and running tests
  - Move E2E testing from "Future Improvements" (now implemented)
- Add comprehensive tests/recordings/README.md documentation

Purpose: Establishes browser automation testing infrastructure with
real workflow recordings, enabling regression testing and interaction
documentation for all game configuration combinations.

package.json

@@ -6,7 +6,10 @@
     "dev": "astro dev --host",
     "build": "astro build",
     "preview": "astro preview",
-    "astro": "astro"
+    "astro": "astro",
+    "test:record": "playwright codegen http://localhost:3000",
+    "test:e2e": "playwright test",
+    "test:replay": "playwright test"
   },
   "dependencies": {
     "@astrojs/preact": "^4.1.0",
@@ -14,6 +17,8 @@
     "preact": "^10.26.8"
   },
   "devDependencies": {
-    "@types/node": "^24.0.3"
+    "@playwright/test": "^1.56.1",
+    "@types/node": "^24.0.3",
+    "playwright": "^1.56.1"
   }
 }