refactor: migrate UI to Preact components and remove legacy Astro/JS

- Replaced all .astro components with .jsx Preact components and added corresponding CSS modules.
- Updated index.astro to use the new App Preact component; removed legacy script and Astro imports.
- Deleted obsolete .astro component files and main JS logic (src/scripts/index.js, public/scripts/index.js).
- Updated astro.config.mjs for Preact integration.
- Updated package.json and package-lock.json to include @astrojs/preact and preact.
- Updated tsconfig.json for Preact JSX support.
- Refactored index.css to keep only global resets and utility styles.
- All changes relate to Gitea issue #1 (refactor to astro app).

Migrates the UI from Astro/vanilla JS to a modular Preact component architecture, removing all legacy code and aligning the project with modern best practices.
Refs #1

src/components/NewGame.module.css

@@ -0,0 +1,111 @@
+.screen {
+    position: absolute;
+    top: 0;
+    left: 0;
+    width: 100%;
+    min-height: 100vh;
+    display: none;
+    opacity: 0;
+    transform: translateX(100%);
+    transition: transform 0.3s ease, opacity 0.3s ease;
+}
+.screen-content {
+    display: flex;
+    flex-direction: column;
+    min-height: 100vh;
+    padding: 20px;
+    overflow-y: auto;
+    -webkit-overflow-scrolling: touch;
+}
+.screen-title {
+    font-size: 24px;
+    margin-bottom: 20px;
+}
+.player-inputs {
+    display: flex;
+    flex-direction: column;
+    gap: 20px;
+    width: 100%;
+    flex: 1;
+}
+.player-input {
+    margin-bottom: 20px;
+}
+.player-input label {
+    display: block;
+    margin-bottom: 10px;
+    color: #ccc;
+    font-size: 24px;
+}
+.name-input-container {
+    display: flex;
+    gap: 10px;
+}
+.name-select {
+    flex: 1;
+    padding: 30px;
+    border: 2px solid #333;
+    background: #2a2a2a;
+    color: white;
+    font-size: 24px;
+    min-height: 44px;
+}
+.name-input {
+    flex: 2;
+    padding: 30px;
+    border: 2px solid #333;
+    background: #2a2a2a;
+    color: white;
+    font-size: 24px;
+    min-height: 44px;
+}
+.name-select:focus, .name-input:focus {
+    outline: none;
+    border-color: #666;
+}
+.game-settings {
+    margin-top: 20px;
+    width: 100%;
+}
+.setting-group {
+    margin-bottom: 20px;
+}
+.setting-group select {
+    width: 100%;
+    padding: 30px;
+    border: 2px solid #333;
+    background: #2a2a2a;
+    color: white;
+    font-size: 24px;
+    min-height: 44px;
+    padding: 12px;
+}
+.setting-group input {
+    width: 100%;
+    padding: 30px;
+    border: 2px solid #333;
+    background: #2a2a2a;
+    color: white;
+    font-size: 24px;
+}
+.setting-group input:focus {
+    outline: none;
+    border-color: #666;
+}
+.nav-buttons {
+    display: flex;
+    flex-direction: column;
+    gap: 10px;
+    margin: 20px 0 40px 0;
+}
+.btn {
+    flex: 1;
+    min-width: 100px;
+    padding: 20px;
+    color: white;
+    border: none;
+    border-radius: 0;
+    font-size: 20px;
+    cursor: pointer;
+    touch-action: manipulation;
+}