HEL-543: add data hub observability side-channel (provider status, source catalog, lineage)

- New provider_call_log/provider_health tables (additive-only schema),
  wired via a fail-open observability.observe()/record_call() helper.
- Tushare pipeline keeps its existing src_calls record unchanged and now
  also feeds the unified provider_health/provider_call_log side channel.
- Eastmoney/Tencent realtime_serve.py call sites and the iFinD steward
  call site are wrapped with observability.observe() at the call site
  only; no adapter internals, routing, fallback order, or return values
  are touched.
- New read-only admin API endpoints: /admin/api/providers/status,
  /admin/api/source-catalog, /admin/api/lineage,
  /admin/api/lineage/affected.
- New static, read-only source_catalog.py and lineage.py registries
  documenting existing providers/interfaces/datasets and known
  main-site consumers (cited against backend/features/screener and
  backend/features/heaven call sites).
- provider_call_log is purged by the existing pipeline.cleanup() job
  alongside src_calls/job_runs.
- 47 new unit/integration tests covering classification, fail-open
  behavior under DB/log failures, unchanged payloads/exceptions on
  success and failure paths, and the new HTTP endpoints. Full suite:
  173 tests, all green.

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

xiaobai-datahub/datahub/httpapp.py

@@ -122,6 +122,26 @@ class HubRequestHandler(BaseHTTPRequestHandler):
         if path == "/admin/api/sources" and method == "GET":
             self._json(self.hub.admin.sources(), HTTPStatus.OK)
             return
+        if path == "/admin/api/providers/status" and method == "GET":
+            query = parse_query(urlparse(self.path).query)
+            provider = (query.get("provider") or [""])[0]
+            limit = (query.get("limit") or ["50"])[0]
+            self._json(self.hub.admin.providers_status(provider, int(limit or 50)), HTTPStatus.OK)
+            return
+        if path == "/admin/api/source-catalog" and method == "GET":
+            self._json(self.hub.admin.source_catalog(), HTTPStatus.OK)
+            return
+        if path == "/admin/api/lineage" and method == "GET":
+            query = parse_query(urlparse(self.path).query)
+            date = (query.get("date") or [""])[0]
+            self._json(self.hub.admin.lineage(date), HTTPStatus.OK)
+            return
+        if path == "/admin/api/lineage/affected" and method == "GET":
+            query = parse_query(urlparse(self.path).query)
+            provider = (query.get("provider") or [""])[0]
+            interface = (query.get("interface") or [""])[0]
+            self._json(self.hub.admin.lineage_affected(provider, interface), HTTPStatus.OK)
+            return
         if path.startswith("/admin/api/sources/") and path.endswith("/probe") and method == "POST":
             provider = path.split("/")[4]
             self._json(self.hub.admin.probe(provider), HTTPStatus.OK)