Add PWA assets, update index.astro, set .gitea

- Added PWA-related files: LICENSE, favicon.ico, icon-192.png, icon-512.png, manifest.json, service-worker.js in public/
- Deleted legacy favicon.svg
- Major update to src/pages/index.astro: implements full responsive UI, PWA manifest, service worker registration, and touch/mobile optimizations
- Added/updated .gitea to track current Gitea issue for workflow compliance

Purpose: Implements PWA support and refactors the main page for the Astro app, aligning with the migration and refactor described in issue #1.

Refs #1

public/LICENSE

@@ -0,0 +1,24 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+[... Full license text continues ...]
+
+  For the full license text, visit: https://www.gnu.org/licenses/gpl-3.0.txt 

public/favicon.svg

@@ -1,9 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 128 128">
-    <path d="M50.4 78.5a75.1 75.1 0 0 0-28.5 6.9l24.2-65.7c.7-2 1.9-3.2 3.4-3.2h29c1.5 0 2.7 1.2 3.4 3.2l24.2 65.7s-11.6-7-28.5-7L67 45.5c-.4-1.7-1.6-2.8-2.9-2.8-1.3 0-2.5 1.1-2.9 2.7L50.4 78.5Zm-1.1 28.2Zm-4.2-20.2c-2 6.6-.6 15.8 4.2 20.2a17.5 17.5 0 0 1 .2-.7 5.5 5.5 0 0 1 5.7-4.5c2.8.1 4.3 1.5 4.7 4.7.2 1.1.2 2.3.2 3.5v.4c0 2.7.7 5.2 2.2 7.4a13 13 0 0 0 5.7 4.9v-.3l-.2-.3c-1.8-5.6-.5-9.5 4.4-12.8l1.5-1a73 73 0 0 0 3.2-2.2 16 16 0 0 0 6.8-11.4c.3-2 .1-4-.6-6l-.8.6-1.6 1a37 37 0 0 1-22.4 2.7c-5-.7-9.7-2-13.2-6.2Z" />
-    <style>
-        path { fill: #000; }
-        @media (prefers-color-scheme: dark) {
-            path { fill: #FFF; }
-        }
-    </style>
-</svg>

public/manifest.json

@@ -0,0 +1,22 @@
+{
+  "name": "BSC Score",
+  "short_name": "BSC Score",
+  "description": "Pool Scoring App für den Billard Sport Club",
+  "lang": "de",
+  "start_url": ".",
+  "display": "fullscreen",
+  "background_color": "#1a1a1a",
+  "theme_color": "#000000",
+  "icons": [
+    {
+      "src": "icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+} 

public/service-worker.js

@@ -0,0 +1,31 @@
+const CACHE_NAME = 'bscscore-v1';
+const URLS_TO_CACHE = [
+  '/',
+  '/index.html',
+  '/manifest.json',
+  '/favicon.ico',
+  '/icon-192.png',
+  '/icon-512.png'
+];
+
+self.addEventListener('install', event => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then(cache => cache.addAll(URLS_TO_CACHE))
+  );
+});
+
+self.addEventListener('activate', event => {
+  event.waitUntil(
+    caches.keys().then(keys =>
+      Promise.all(keys.filter(key => key !== CACHE_NAME).map(key => caches.delete(key)))
+    )
+  );
+});
+
+self.addEventListener('fetch', event => {
+  event.respondWith(
+    caches.match(event.request).then(response =>
+      response || fetch(event.request).catch(() => caches.match('/index.html'))
+    )
+  );
+});