[AZ-320] Add C11 IdempotentRetryTileUploader decorator

Wraps HttpTileUploader (AZ-319) with two bounded retry budgets:

- In-call (per-batch) — re-invokes inner on PARTIAL outcome up to
  `max_in_call_retries` times with capped exponential backoff
  (`min(base ** attempt_number, cap)`). On exhaustion: surfaces an
  operator hint via `next_retry_at_s = now + backoff_cap_s`.
- Per-tile (cross-call) — atomically increments c6's
  `tiles.upload_attempts` counter for every rejection; once a tile
  hits `max_per_tile_attempts` it is forward-only transitioned to
  `voting_status = upload_giveup` (excluded from `pending_uploads`).
  Each transition emits FDR `kind="c11.upload.giveup"` plus an
  ERROR log.

C6 contract changes (AZ-303 v1.3.0):
- VotingStatus.UPLOAD_GIVEUP added (forward-only from PENDING/TRUSTED).
- TileMetadataStore.increment_upload_attempts(tile_id) -> int added
  with NotImplementedError default for backwards-compat.
- Migration 0003_c11_upload_attempts: additive column +
  widened ck_tiles_voting_status (preserves IS NULL clause).

C11 wiring:
- C11RetryConfig + disable_retry_decorator on C11Config.
- build_tile_uploader wraps in decorator by default; bypass flag
  returns the bare HttpTileUploader. New `clock` keyword.

Cross-component isolation honoured (AZ-507): the decorator declares
`_RetryMetadataStoreLike` Protocol cut over c6's TileMetadataStore
and references `UPLOAD_GIVEUP` via a local string constant — no c6
imports.

Tests: 13 decorator + 1 conformance + 2 factory bypass + AC-6 enum
update + alembic head bump + AZ-272 schema fixture. 238 passed across
c11/c6/fdr suites; pre-existing perf microbenches unrelated.

Code review: PASS_WITH_WARNINGS (5 Low/Informational findings,
docs-level or downstream-CI-blocked). See
_docs/03_implementation/reviews/batch_41_review.md.

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

tests/unit/test_ac5_alembic.py

@@ -25,8 +25,11 @@ def test_head_revision_matches_latest_migration() -> None:
 
     AZ-263 originally pinned this to ``0001_initial``; AZ-304 advanced the head
     to ``0002_c6_tile_identity_and_lru`` (additive on AZ-263 — see
-    ``_docs/02_tasks/todo/AZ-304_c6_postgres_schema.md``). Future migrations
-    update this assertion in lockstep with the new head.
+    ``_docs/02_tasks/todo/AZ-304_c6_postgres_schema.md``). AZ-320 added
+    ``0003_c11_upload_attempts`` (additive — adds the
+    ``tiles.upload_attempts`` counter and widens the
+    ``ck_tiles_voting_status`` constraint to admit ``upload_giveup``).
+    Future migrations update this assertion in lockstep with the new head.
     """
     # Arrange
     cwd = os.getcwd()
@@ -40,7 +43,7 @@ def test_head_revision_matches_latest_migration() -> None:
         os.chdir(cwd)
 
     # Assert
-    assert list(heads) == ["0002_c6_tile_identity_and_lru"], f"unexpected heads: {heads}"
+    assert list(heads) == ["0003_c11_upload_attempts"], f"unexpected heads: {heads}"
 
 
 @pytest.mark.parametrize(