Add PWA support: installable standalone app with safe area handling

- Service worker, manifest, and SVG icon for PWA installability
- Root /sw.js route for full-scope service worker registration
- Meta tags: theme-color, apple-mobile-web-app, viewport-fit=cover
- Safe area insets for notched phones (container, mini-player, footer, banner)
- Dynamic theme-color sync on light/dark toggle
- Overscroll prevention and touch-action optimization
- Hide mini-player prev/next buttons on small screens
- Updated README with PWA and new feature documentation

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

media_server/static/css/styles.css

@@ -3067,6 +3067,10 @@ footer .separator {
         padding-top: calc(0.5rem + 2px);
     }
 
+    .mini-nav-btn {
+        display: none;
+    }
+
     .mini-player-info {
         min-width: 120px;
     }
@@ -3164,3 +3168,72 @@ footer .separator {
         justify-content: flex-start;
     }
 }
+
+/* ========================================
+   PWA Standalone & Mobile Polish
+   ======================================== */
+
+html {
+    overscroll-behavior: none;
+}
+
+/* Safe area insets for notched phones (viewport-fit=cover) */
+.container {
+    padding-left: max(0.75rem, env(safe-area-inset-left));
+    padding-right: max(0.75rem, env(safe-area-inset-right));
+}
+
+.mini-player {
+    padding-bottom: max(0.75rem, env(safe-area-inset-bottom));
+    padding-left: max(1rem, env(safe-area-inset-left));
+    padding-right: max(1rem, env(safe-area-inset-right));
+}
+
+footer {
+    padding-bottom: max(0.75rem, env(safe-area-inset-bottom));
+}
+
+body.mini-player-visible footer {
+    padding-bottom: calc(70px + env(safe-area-inset-bottom, 0px));
+}
+
+.connection-banner {
+    padding-top: max(10px, env(safe-area-inset-top));
+}
+
+/* Touch optimization: eliminate 300ms tap delay */
+.controls button,
+.mini-controls button,
+.mini-control-btn,
+.tab-btn,
+.header-btn,
+.header-link,
+.mute-btn,
+.vinyl-toggle-btn,
+.view-toggle-btn,
+.browser-item,
+.browser-list-item,
+.script-btn,
+.action-btn {
+    touch-action: manipulation;
+}
+
+@media (max-width: 600px) {
+    .container {
+        padding-left: max(0.5rem, env(safe-area-inset-left));
+        padding-right: max(0.5rem, env(safe-area-inset-right));
+    }
+
+    .mini-player {
+        padding-bottom: max(0.5rem, env(safe-area-inset-bottom));
+        padding-left: max(0.75rem, env(safe-area-inset-left));
+        padding-right: max(0.75rem, env(safe-area-inset-right));
+    }
+}
+
+@media (display-mode: standalone) {
+    body {
+        overscroll-behavior-y: none;
+        -webkit-overflow-scrolling: touch;
+    }
+}