Round-3 review caught second column mismatch. `domrf_kn_objects` has
`snapshot_date` (DATE NOT NULL), no `updated_at` — verified via
information_schema. CAST drop (snapshot_date is already DATE).
Worker used wrong column name in KPI 3 query — would always raise
UndefinedColumn at runtime and fall back to hardcoded defaults instead
of returning real data. Verified column name via vault
Objective_Data_Source_May17.md + earlier postgres MCP query.
Also resolves merge with hotfix #337 (pilot.py EmailStr drop) — no
actual conflict, just sync with new main.
New router backend/app/api/v1/landing.py with GET /api/v1/landing/stats.
Queries domrf_kn_objects, rosreestr_deals_* (pg_class), objective_lots,
objective_complex_mapping; falls back to hardcoded defaults on empty DB.
