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/db.py

@@ -8,6 +8,7 @@ from pathlib import Path
 from typing import Any
 
 from datahub.datasets_ext import EXTENDED_DATASET_TABLES, EXTENDED_SCHEMA
+from datahub.observability import OBS_SCHEMA
 from datahub.timeutil import isoformat
 
 _BASE_SCHEMA = """
@@ -296,7 +297,7 @@ CREATE INDEX IF NOT EXISTS idx_eod_bars_date ON eod_bars(trade_date, batch_id);
 CREATE INDEX IF NOT EXISTS idx_calendar_open ON trade_calendar(is_open, cal_date);
 """
 
-SCHEMA = _BASE_SCHEMA + EXTENDED_SCHEMA
+SCHEMA = _BASE_SCHEMA + EXTENDED_SCHEMA + OBS_SCHEMA
 
 DATASET_TABLES = {
     "daily": ("eod_bars", "staging_bars"),