feat(cdc): add Re-sync sources button + auto-heal for Debezium connectors

- streaming_ops: add connector status discovery, manual resync endpoint
  (POST /api/pipeline/streaming/resync), connectors status endpoint, and a
  background connector_autoheal_loop that restarts FAILED tasks automatically
- main: wire connector_autoheal_loop into app lifespan
- api.ts: add resyncSources() helper
- ChangesView: add "Re-sync sources" header button with live status

ui/src/lib/api.ts

@@ -115,6 +115,18 @@ export async function fetchChangeStats(minutes = 15): Promise<CdcStats | null> {
   return fetchJson<CdcStats>(`/api/changes/stats?minutes=${minutes}`, 8000)
 }
 
+export type ConnectorState = { name: string; state?: string; failed?: number[] }
+export type ResyncResult = { ok: boolean; restarted?: string[]; healthy?: number; total?: number; after?: ConnectorState[] }
+
+export async function resyncSources(force = true): Promise<ResyncResult | null> {
+  const r = await fetch('/api/pipeline/streaming/resync', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ force }),
+  })
+  return r.ok ? ((await r.json()) as ResyncResult) : null
+}
+
 export async function fetchAgentOpsStatus() {
   return fetchJson<Record<string, unknown>>('/api/agent-ops/status', 8000)
 }