feat: add auto-update system with release checking, notification UI, and install-type-aware apply

- Abstract ReleaseProvider interface (Gitea impl, swappable for GitHub/GitLab)
- Background UpdateService with periodic checks, debounce, dismissed version persistence
- Install type detection (installer/portable/docker/dev) with platform-aware asset matching
- Download with progress events, silent NSIS reinstall, portable ZIP/tarball swap scripts
- Version badge pulse animation, dismissible banner with icon buttons, Settings > Updates tab
- Single source of truth: pyproject.toml version via importlib.metadata, CI stamps tag with sed
- API: GET/POST status, check, dismiss, apply, GET/PUT settings
- i18n: en, ru, zh (27+ keys each)

server/src/wled_controller/static/css/layout.css

@@ -109,6 +109,58 @@ h2 {
     padding: 2px 8px;
     border-radius: 10px;
     letter-spacing: 0.03em;
+    transition: background 0.3s, color 0.3s, box-shadow 0.3s;
+}
+
+#server-version.has-update {
+    background: var(--warning-color);
+    color: #fff;
+    cursor: pointer;
+    animation: updatePulse 2s ease-in-out infinite;
+}
+
+@keyframes updatePulse {
+    0%, 100% { box-shadow: 0 0 0 0 rgba(255, 152, 0, 0.4); }
+    50% { box-shadow: 0 0 0 4px rgba(255, 152, 0, 0); }
+}
+
+/* ── Update banner ── */
+.update-banner {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 10px;
+    padding: 6px 16px;
+    background: var(--bg-secondary);
+    border-bottom: 2px solid var(--primary-color);
+    color: var(--text-color);
+    font-size: 0.85rem;
+    font-weight: 600;
+    animation: bannerSlideDown 0.3s var(--ease-out);
+}
+
+.update-banner-text {
+    color: var(--primary-color);
+}
+
+.update-banner-action {
+    padding: 4px;
+    background: transparent;
+    border: none;
+    color: var(--text-secondary);
+    cursor: pointer;
+    border-radius: var(--radius-sm);
+    transition: color 0.15s, background 0.15s;
+}
+
+.update-banner-action:hover {
+    color: var(--primary-color);
+    background: var(--border-color);
+}
+
+@keyframes bannerSlideDown {
+    from { transform: translateY(-100%); opacity: 0; }
+    to { transform: translateY(0); opacity: 1; }
 }
 
 .status-badge {