[AZ-611] Add --skip-auto-sync flag to bypass AC-9 validator

Mid-flight fixtures (Derkachi) and stationary-still scenarios
(FT-P-01) have no take-off spike for the IMU detector and produce
false-positive video motion onsets, so the AC-9 frame-window
validator rejects every plausible offset. Add an operator-acknowledged
opt-out: a new ReplayConfig.skip_auto_sync_validation flag that
suppresses validation, paired with a hard requirement that
time_offset_ms also be set (silent-zero guard at both schema and
adapter layers).

Wired through schema -> CLI (--skip-auto-sync) -> composition root
-> ReplayInputAdapter; Derkachi e2e fixture now passes
time_offset_ms=0 + skip_auto_sync=True by default since the synth
tlog and the video share the same t=0 anchor by construction.

5 new unit tests:
  * schema gate rejects skip=True without manual offset
  * schema gate accepts the legal pair
  * default field value is False (default-construction safety)
  * adapter constructor mirrors the schema gate
  * adapter open() bypasses validate_offset_or_fail when flag is set

All 38 unit tests in test_az401 + test_az405 pass on Mac.

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

tests/e2e/replay/conftest.py

@@ -149,11 +149,22 @@ class ReplayRunResult:
 def replay_runner(derkachi_replay_inputs: DerkachiReplayInputs) -> Any:
     """Return a callable that invokes the ``gps-denied-replay`` console-script.
 
-    The callable accepts keyword overrides for ``pace`` and
-    ``time_offset_ms``; everything else is taken from
-    ``derkachi_replay_inputs``. Output is written to a fresh path per
-    invocation so determinism comparisons (AC-5) get two independent
-    files.
+    The callable accepts keyword overrides for ``pace``,
+    ``time_offset_ms``, and ``skip_auto_sync`` (AZ-611); everything
+    else is taken from ``derkachi_replay_inputs``. Output is written
+    to a fresh path per invocation so determinism comparisons (AC-5)
+    get two independent files.
+
+    Derkachi is a mid-flight fixture (no take-off spike) and the only
+    motion the video detector sees in the first 60 s is camera shake
+    and scenery change — neither tlog nor video can produce a
+    reliable auto-sync signal. The synth tlog and the video share
+    the same ``t=0`` anchor by construction (see
+    ``_tlog_synth.py``), so the correct offset is exactly ``0``. The
+    fixture defaults reflect that — heavy ACs pass
+    ``time_offset_ms=0`` + ``skip_auto_sync=True`` so the run never
+    touches the AC-9 validator that would otherwise reject the
+    fixture's false-positive video motion onset.
     """
 
     binary = shutil.which("gps-denied-replay")
@@ -169,7 +180,12 @@ def replay_runner(derkachi_replay_inputs: DerkachiReplayInputs) -> Any:
 
     invocation_count = {"n": 0}
 
-    def _run(*, pace: str = "asap", time_offset_ms: int | None = None) -> ReplayRunResult:
+    def _run(
+        *,
+        pace: str = "asap",
+        time_offset_ms: int | None = 0,
+        skip_auto_sync: bool = True,
+    ) -> ReplayRunResult:
         import time
 
         invocation_count["n"] += 1
@@ -195,6 +211,8 @@ def replay_runner(derkachi_replay_inputs: DerkachiReplayInputs) -> Any:
         ]
         if time_offset_ms is not None:
             argv.extend(["--time-offset-ms", str(time_offset_ms)])
+        if skip_auto_sync:
+            argv.append("--skip-auto-sync")
         t0 = time.monotonic()
         completed = subprocess.run(
             argv,