[AZ-895] Deprecate replay auto-sync surface; file AZ-908 follow-up

Option A (minimum-deprecation, 2 SP) per user complexity-budget
decision. Auto-sync stays importable as a raising stub for one cycle
so external callers see a clean ReplayInputAdapterError instead of an
ImportError. Full physical removal is filed as AZ-908 (cycle-5+ backlog).

Production:
- auto_sync.py: 700+ LOC -> 56-line no-op stub raising
  "auto-sync removed; supply --imu CSV instead"
- tlog_video_adapter.py: 700+ LOC -> 105-line deprecated stub;
  ReplayInputAdapter.open() raises immediately, close() is a no-op
- _replay_branch.py: dropped legacy auto-sync branch +
  _build_auto_sync_config; _validate_replay_paths now requires
  imu_csv_path; replay_input_adapter_factory parameter removed
- cli/replay.py: --time-offset-ms / --skip-auto-sync / --auto-trim
  emit DeprecationWarning + stderr line; values ignored
- tlog_replay_adapter.py + tlog_ground_truth.py docstrings: AUDIT-ONLY

Tests:
- DELETED test_az405_auto_sync, test_az405_replay_input_adapter,
  test_az698_window_alignment (covered code no longer runs)
- ADDED test_az895_auto_sync_deprecated_stub (5 parametrised, pins AC-1)
- test_az402_replay_cli: deprecation warnings + ignored-value asserts
- test_az401_compose_root_replay: new imu_csv_path-required gate;
  deleted the calibration-loading test that relied on the removed
  replay_input_adapter_factory injection point
- test_derkachi_real_tlog: xfail reason refreshed to AZ-848 + AZ-883
  (AC-4 "AZ-848-scoped reason")

Docs:
- module-layout.md: replay_input file list flags deprecated modules,
  adds csv_ground_truth.py
- _dependencies_table.md: +AZ-908 row, preamble + totals updated
  (179 -> 180 tasks, 567 -> 570 SP)
- AZ-908 backlog spec added; AZ-895 spec moved todo -> done
- batch_03_cycle4_report.md written

Touched-module tests green (111 passed, 1 skipped). Full unit suite
green: 2287 passed, 85 skipped, 1 deselected (pre-existing flaky perf
test, unrelated).

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

_docs/02_tasks/done/AZ-895_deprecate_auto_sync_surface.md

@@ -0,0 +1,39 @@
+# Replay: deprecate auto_sync surface; tlog adapter → audit-only
+
+**Task**: AZ-895_deprecate_auto_sync_surface
+**Name**: Remove the tlog+video auto-sync infrastructure and reframe `tlog_replay_adapter.py` as audit-only, now that AZ-894 ships the CSV-driven primary path
+**Description**: User decision (2026-05-26): the test/demo replay path will accept a paired (video, CSV) input from the operator instead of auto-syncing a tlog and video. Auto-sync is unnecessary in production (single edge device, single clock by design) and over-engineered for test (the CSV already encodes the alignment).
+
+**Complexity**: 2 SP
+**Dependencies**: AZ-894 (must ship first — the CSV adapter is the replacement)
+**Component**: replay_input (auto_sync.py, tlog_video_adapter.py), cli/replay, runtime_root/_replay_branch
+**Tracker**: AZ-895 (https://denyspopov.atlassian.net/browse/AZ-895)
+**Parent Epic**: (none — cycle-4 replay-input redesign)
+
+## Touch list
+
+- `src/gps_denied_onboard/replay_input/auto_sync.py` — delete or convert to a clear no-op that raises `ReplayInputAdapterError("auto-sync removed; supply --imu CSV instead")`
+- `src/gps_denied_onboard/replay_input/tlog_video_adapter.py` — strip auto-sync invocations
+- `src/gps_denied_onboard/cli/replay.py` — remove `--time-offset-ms` / `--skip-auto-sync-validation` flags (or mark deprecated with one-cycle warning)
+- `src/gps_denied_onboard/runtime_root/_replay_branch.py` — strip auto-sync wiring
+- `tests/unit/replay_input/test_az405_auto_sync.py` — pass against the new behaviour or delete with rationale recorded in the batch report
+- `tests/e2e/replay/test_derkachi_real_tlog.py` — continues to `@xfail` with the AZ-848-scoped reason; nothing in this ticket fixes the underlying tlog-clock bug
+- `tlog_replay_adapter.py` / `tlog_ground_truth.py` — module docstrings updated to call out the new audit-only / one-shot-export roles
+
+## Acceptance Criteria
+
+- **AC-1**: `auto_sync.py` is either deleted or made into a clear no-op that raises `ReplayInputAdapterError("auto-sync removed; supply --imu CSV instead")`.
+- **AC-2**: All references to `--time-offset-ms` / `--skip-auto-sync-validation` flags in the CLI are removed or marked deprecated with a one-cycle deprecation warning.
+- **AC-3**: `test_az405_auto_sync` tests either pass against the new behaviour or are deleted with rationale recorded in the batch report.
+- **AC-4**: `test_derkachi_real_tlog.py` continues to `@xfail` with the AZ-848-scoped reason; nothing in this ticket fixes the underlying tlog-clock bug.
+- **AC-5**: Module docstrings of `tlog_replay_adapter.py` and `tlog_ground_truth.py` are updated to call out their new audit-only / one-shot-export roles.
+
+## Out of scope
+
+- AZ-848 / AZ-883 structural fix — they stay open as backlog (tlog path is still broken, just no longer the primary path).
+- New CSV export tooling for arbitrary tlogs — future ticket.
+
+## References
+
+- Cycle-3 retro: `_docs/06_metrics/retro_2026-05-26.md`
+- Companion: AZ-894 (CSV adapter — must land first), AZ-896 (docs), AZ-897 (UI)