[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/backlog/AZ-908_replay_auto_sync_hard_removal.md

@@ -0,0 +1,59 @@
+# Replay: hard removal of deprecated auto-sync surface (AZ-895 follow-up)
+
+**Task**: AZ-908_replay_auto_sync_hard_removal
+**Name**: Cycle-5+ cleanup that physically removes the auto-sync surface AZ-895 deprecated
+**Description**: Follow-up to AZ-895 (cycle 4). AZ-895 made the auto_sync surface a no-op and deprecated the CLI flags (`--time-offset-ms`, `--skip-auto-sync`, `--auto-trim`) with one-cycle warnings, but left the call sites, config fields, and interface DTOs intact for backward compat. AZ-908 completes the removal in cycle 5+ after a one-cycle deprecation window has passed.
+
+**Complexity**: 3 SP
+**Dependencies**: AZ-895 (hard — must ship first; AZ-908 removes what AZ-895 deprecated), AZ-842 (hard — replay protocol docs coordinate)
+**Component**: replay_input (auto_sync.py + tlog_video_adapter.py + interface.py), cli/replay, runtime_root/_replay_branch + runtime_root/__init__, config/schema + config/loader + config/__init__, replay_api/app
+**Tracker**: AZ-908 (https://denyspopov.atlassian.net/browse/AZ-908)
+**Parent Epic**: (none — cycle-4 replay-input redesign follow-up)
+
+## Why
+
+Auto-sync surface is dead in production code: AZ-894 (cycle 4) made the CSV-driven path mandatory via required `--imu`, and AZ-895 (cycle 4) deprecated the surface. After one cycle's deprecation window the deprecation warnings should fire in real CI runs (if any operator scripts still pass the deprecated flags); that surface area can then be removed without breaking anyone.
+
+## Touch list (production)
+
+- DELETE `src/gps_denied_onboard/replay_input/auto_sync.py` (currently a no-op stub from AZ-895)
+- DELETE `src/gps_denied_onboard/replay_input/tlog_video_adapter.py` (currently a deprecated coordinator from AZ-895)
+- Drop `AutoSyncConfig`, `AutoSyncDecision`, `AlignedWindow` DTOs from `replay_input/interface.py`. Drop `auto_sync_result` + `aligned_window` fields from `ReplayInputBundle`.
+- Drop `--time-offset-ms`, `--skip-auto-sync`, `--auto-trim` CLI flags from `cli/replay.py` entirely
+- Drop `ReplayConfig.time_offset_ms`, `.skip_auto_sync_validation`, `.auto_trim`, `.auto_sync` from `config/schema.py`. Drop `ReplayAutoSyncConfig` class.
+- Drop `REPLAY_TIME_OFFSET_MS` env var + `auto_sync` block handling from `config/loader.py`
+- Update `runtime_root/_replay_branch.py` to drop any lingering imports / dead code
+- Update `runtime_root/__init__.py` if it references removed symbols
+- Update `replay_api/app.py` if it references removed symbols
+- Update `e2e/fixtures/sitl_replay_builder/builder.py` if it references removed symbols
+
+## Touch list (tests)
+
+- Delete remaining auto-sync test residue (no-op stub tests from AZ-895)
+- Update CLI tests to drop deprecated-flag assertions (the flags no longer exist)
+- Confirm `test_az401_compose_root_replay.py` is clean
+
+## Touch list (docs)
+
+- Update `_docs/02_document/module-layout.md` replay_input file list — remove deleted entries
+- Update `_docs/02_document/contracts/replay/replay_protocol.md` — remove auto-sync surface narrative (coordinate with AZ-842)
+- Update `_docs/02_document/contracts/replay/csv_replay_format.md` cross-references
+
+## Acceptance Criteria
+
+- **AC-1**: All files listed under "DELETE" above are removed from the workspace
+- **AC-2**: Unit tests pass with no auto-sync, AutoSyncConfig, AutoSyncDecision, or AlignedWindow symbols in `src/gps_denied_onboard/**`
+- **AC-3**: CLI `--help` output does not mention `--time-offset-ms`, `--skip-auto-sync`, or `--auto-trim`
+- **AC-4**: `_docs/02_document/module-layout.md` does not mention `auto_sync.py` or `tlog_video_adapter.py`
+- **AC-5**: `tests/e2e/replay/test_derkachi_real_tlog.py` continues to `@xfail` with AZ-848-scoped reason
+
+## Out of scope
+
+- AZ-848 / AZ-883 structural fix (tlog clock bug) — unchanged from AZ-895
+- Replacing the deprecated coordinator with something else — the CSV path is the replacement (see `_replay_branch._build_csv_bundle`)
+
+## References
+
+- Companion in cycle 4: AZ-894 (CSV adapter), AZ-895 (deprecation)
+- Decision audit trail: this file + AZ-895 batch_03_cycle4_report.md
+- User decision 2026-05-26 (cycle-4 /autodev batch 3): chose Option A (light deprecation now, file AZ-908 for hard removal in cycle 5+) over Option B (full removal in cycle 4).