v0.2.2 - spark-vllm-docker update checks + Apply Update

Backend:
- updates.py: get_update_status() runs git fetch + git rev-list --left-right --count HEAD...origin/main to learn ahead/behind/dirty, plus git log for pending commits
- UpdateManager class with asyncio.Lock; one update at a time
- POST /api/updates/apply triggers "git pull --ff-only && ./build-and-copy.sh -c" over SSH with streamed log + phase detection (Pulling / Building the vLLM container / Copying to peer Sparks)
- GET /api/updates returns {ok, behind, ahead, dirty, current, log[], branch}

Frontend:
- Persistent banner near footer: hidden when up-to-date, blue when N commits behind, warn (orange) when local dirty changes block update
- 'Show details' expands a list of pending commits
- 'Apply update' triggers the long-running build with phase + elapsed timer + collapsible logs
- Confirmation dialog explains the 5–40 min duration

Package: bump 0.2.2:0

image/app/static/style.css

@@ -217,6 +217,27 @@ main {
   word-break: break-word;
 }
 
+/* ===== Update banner ===== */
+
+.update-banner {
+  background: var(--surface);
+  border: 1px solid rgba(96, 165, 250, 0.4);
+  border-radius: var(--radius);
+  padding: 10px 14px;
+  margin-top: 18px;
+  font-size: 13px;
+}
+.update-banner.up-to-date {
+  border-color: var(--border);
+  color: var(--muted);
+}
+.update-banner.warn { border-color: var(--warn); }
+.ub-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
+.ub-row .spacer { flex: 1; }
+#ub-list { margin-top: 8px; }
+#ub-list summary { cursor: pointer; padding: 4px 0; }
+#ub-progress { margin-top: 10px; }
+
 /* ===== Section header (title + action button) ===== */
 
 .section-header {