feat: close STREAMING.md production readiness gaps

- Added run ID + unique segment naming (r-{ISOTIME}/seg-{seq}.m4s)
- Added fsnotify watcher for real-time R2 segment upload (~7s)
- Added atomic manifest publication (temp key → CopyObject)
- Fixed manifest Cache-Control: public, max-age=1, s-maxage=2, must-revalidate
- Added hls.js error recovery: bounded retries (5x), exponential backoff, reconnecting UI
- Enriched /health endpoint: run_id, active_item, last_segment_seq, last_r2_pub, consecutive_failures, unhealthy detection
- Updated tests: HealthHandler (new fields + unhealthy), player error recovery test
- Updated TODO.md, BACKLOG.md, DONE.md, MEMORY.md

frontend/src/style.css

@@ -1056,3 +1056,40 @@ select {
     scroll-behavior: auto !important;
   }
 }
+
+/* Reconnecting overlay (player error recovery) */
+.reconnecting-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.85);
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: var(--space-4, 1rem);
+  z-index: 1000;
+  backdrop-filter: blur(8px);
+}
+
+.reconnecting-overlay.hidden {
+  display: none;
+}
+
+.reconnecting-spinner {
+  width: 48px;
+  height: 48px;
+  border: 3px solid var(--line, #2a2a2a);
+  border-top-color: var(--brand, #587792);
+  border-radius: 50%;
+  animation: lv-spin 0.8s linear infinite;
+}
+
+@keyframes lv-spin {
+  to { transform: rotate(360deg); }
+}
+
+#reconnecting-text {
+  color: var(--ink-0, #ede8e6);
+  font-family: var(--font-body);
+  font-size: 1.125rem;
+}