[AZ-305] c6 PostgresFilesystemStore: TileStore + TileMetadataStore impl

Adds the production PostgresFilesystemStore implementing both protocols
in a single class. Filesystem-backed JPEG I/O (atomic sidecar write,
read-only mmap) + Postgres-backed metadata (spatial bbox, LRU, voting,
upload bookkeeping). Wires composition via `from_config` classmethod.

Key behaviors:
- AC-3 strict reading: INSERT runs first inside an open transaction;
  duplicate-key collisions raise `TileMetadataError` BEFORE any byte is
  written, leaving the original file + sidecar byte-identical. Atomic
  sidecar write happens inside the same transaction; commit closes it.
  Comp-delete remains as a safety net for the rare commit-after-write
  failure path.
- AC-2 content-hash gate runs before any I/O.
- Construction performs an orphan-file reconciliation scan and emits an
  INFO `c6.store.construct` log with steady-state stats.

Adds `c6.write` and `c6.write_failed` FDR record kinds (schema v1.1.0,
forward-compatible) and a thin operator CLI at
`c6_tile_cache.tools dump` for inspection.

Dependencies: adds `psycopg-pool>=3.2,<4.0` for the connection pool used
on the F3 read-hot path.

Tests: 25 new tests for c6_tile_cache cover AC-1..AC-15 plus
MmapTilePixelHandle + helper round-trips. Full Tier-2 unit suite passes
(1215 passed, 8 skipped, 1 pre-existing unrelated failure
`test_ac8_read_host_tuple_on_jetson` — missing `pynvml` on macOS,
Jetson-only).

Co-authored-by: Cursor <cursoragent@cursor.com>

pyproject.toml

@@ -24,6 +24,10 @@ dependencies = [
     # available.
     "opencv-python>=4.11.0.86,<4.12",
     "psycopg[binary]>=3.1",
+    # AZ-305 / E-C6: `PostgresFilesystemStore` uses ConnectionPool to amortise
+    # pool startup across the read-heavy `read_tile_pixels` path. Pinned to the
+    # 3.x line in lockstep with `psycopg` itself.
+    "psycopg-pool>=3.2,<4.0",
     "sqlalchemy>=2.0",
     "alembic>=1.13",
     "pymavlink>=2.4",