Replaces the AZ-305 pass-through _evaluate_freshness hook with the
production FreshnessGate. Loads tile_freshness_rules + sector
classifications once at construction, builds an rtree index, and on
every evaluate() either returns metadata unchanged (FRESH), stamps
freshness_label=DOWNGRADED (stable_rear + stale), or raises
FreshnessRejectionError carrying tile_id / age_seconds /
classification / rule diagnostics (active_conflict + stale).
Constructed inside PostgresFilesystemStore.from_config; the public
storage_factory signature is preserved so AZ-305 unit tests still
build the store with freshness_gate=None for the pass-through path.
FDR schema bumped to v1.2.0: adds c6.freshness.rejected and
c6.freshness.downgraded kinds (non-breaking; v1.1 readers route them
opaquely). Operator CLI `python -m c6_tile_cache.freshness_gate
explain` dry-runs the decision for a (lat, lon, capture_ts).
Adjacent hygiene: c6_tile_cache.tools._dump_tile now passes
os.environ to load_config (AZ-305 regression — load_config requires
the env mapping).
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh
39ff47087f