feat: add release notes overlay with Markdown rendering

- Replace truncated plaintext release notes with full-screen overlay
  rendered via `marked` library
- Server reconnection does a hard page reload instead of custom event

server/src/wled_controller/static/css/modal.css

@@ -448,6 +448,79 @@
     min-height: 0;
 }
 
+/* ── Release notes content ─────────────────────────────────── */
+
+.release-notes-content {
+    flex: 1;
+    overflow-y: auto;
+    padding: 1rem 1.5rem;
+    font-size: 0.9rem;
+    line-height: 1.6;
+    color: var(--text-color);
+    background: var(--bg-secondary);
+    border-radius: 8px;
+}
+
+.release-notes-content h2,
+.release-notes-content h3,
+.release-notes-content h4 {
+    margin: 1.2em 0 0.4em;
+    color: var(--text-color);
+}
+
+.release-notes-content h2 { font-size: 1.2rem; }
+.release-notes-content h3 { font-size: 1.05rem; }
+.release-notes-content h4 { font-size: 0.95rem; }
+
+.release-notes-content pre {
+    background: #0d0d0d;
+    color: #d4d4d4;
+    padding: 0.75rem 1rem;
+    border-radius: 6px;
+    overflow-x: auto;
+    font-size: 0.82rem;
+}
+
+.release-notes-content code {
+    background: var(--bg-tertiary, #2a2a2a);
+    padding: 0.15em 0.4em;
+    border-radius: 3px;
+    font-size: 0.88em;
+}
+
+.release-notes-content pre code {
+    background: none;
+    padding: 0;
+}
+
+.release-notes-content a {
+    color: var(--primary-color);
+}
+
+.release-notes-content hr {
+    border: none;
+    border-top: 1px solid var(--border-color);
+    margin: 1rem 0;
+}
+
+.release-notes-content table {
+    width: 100%;
+    border-collapse: collapse;
+    margin: 0.5rem 0;
+}
+
+.release-notes-content th,
+.release-notes-content td {
+    border: 1px solid var(--border-color);
+    padding: 0.4rem 0.6rem;
+    text-align: left;
+    font-size: 0.85rem;
+}
+
+.release-notes-content th {
+    background: var(--bg-tertiary, #2a2a2a);
+}
+
 /* ── Log viewer base ───────────────────────────────────────── */
 
 .log-viewer-output {