[AZ-599] Batch 79: FT-P-02 Derkachi builder + _common.py extraction

- Add build_p02_fixtures.py: IMU CSV → tlog conversion (RAW_IMU +
  ATTITUDE pairs, centidegrees→radians yaw) and orchestrator that
  runs gps-denied replay against Derkachi MP4 + generated tlog,
  verifying ≥1 record_type="estimate" in the FDR archive.
- Extract run_gps_denied_replay + FDR-parent-dir helpers into
  sitl_replay_builder/_common.py; refactor build_p01_fixtures.py
  to import from _common (b78 tests preserved).
- Add 20 unit tests under e2e/_unit_tests/fixtures/test_sitl_
  replay_builder_p02.py covering AC-1..AC-5; total unit suite
  686/686 passing (regression gate AC-6).
- README updated to document FT-P-01 + FT-P-02 builders.
- Advance autodev state: last_completed_batch=79, current_batch=80;
  prune verbose detail blob.

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

e2e/fixtures/sitl_replay_builder/build_p01_fixtures.py

@@ -34,13 +34,18 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import Callable, Iterable, Sequence
 
+from e2e.fixtures.sitl_replay_builder._common import (
+    DEFAULT_CLI_BIN,
+    run_gps_denied_replay,
+    write_observer_fixture,
+)
+
 _LOG = logging.getLogger(__name__)
 
 DEFAULT_FPS = 1.0
 DEFAULT_TLOG_DURATION_S = 120
 DEFAULT_TLOG_HZ = 200
 DEFAULT_FDR_KIND = "outbound_position_estimate"
-DEFAULT_CLI_BIN = "gps-denied-replay"
 
 
 @dataclass(frozen=True)
@@ -214,40 +219,7 @@ def _pack_attitude_zero(time_boot_ms: int) -> bytes:
 
 
 # Step 3 — drive `gps-denied-replay` against the generated video+tlog
-
-
-def run_gps_denied_replay(
-    video: Path,
-    tlog: Path,
-    fdr_out: Path,
-    *,
-    cli_bin: str = DEFAULT_CLI_BIN,
-    time_offset_ms: int = 0,
-    extra_args: Sequence[str] = (),
-    _runner: Callable[[Sequence[str]], subprocess.CompletedProcess] | None = None,
-) -> subprocess.CompletedProcess:
-    """Run ``gps-denied-replay`` as a subprocess.
-
-    Bypasses auto-sync via ``--time-offset-ms 0`` because the synthetic
-    stationary tlog has no take-off signal to detect.
-
-    Raises ``subprocess.CalledProcessError`` on non-zero exit code (with
-    the FDR path included in the error message). The default subprocess
-    runner can be swapped via the underscore-prefixed parameter for tests.
-    """
-    fdr_out.parent.mkdir(parents=True, exist_ok=True)
-    cmd: list[str] = [
-        cli_bin,
-        "--video", str(video),
-        "--tlog", str(tlog),
-        "--time-offset-ms", str(time_offset_ms),
-        "--fdr-out", str(fdr_out),
-        *extra_args,
-    ]
-    _LOG.info("running: %s", " ".join(cmd))
-
-    runner = _runner or (lambda c: subprocess.run(c, check=True, capture_output=True, text=True))
-    return runner(cmd)
+# (`run_gps_denied_replay` is re-exported from `_common.py` so b78 + b79 share one impl.)
 
 
 # Step 4 — extract per-frame outbound estimates from the FDR JSONL
@@ -334,28 +306,7 @@ def write_outbound_messages_fixture(
     output_path.write_text(json.dumps({"messages": messages}, indent=2))
 
 
-def write_observer_fixture(output_path: Path) -> None:
-    """Write minimal `observer_<fc_kind>_<host>.json` so `get_observer` succeeds.
-
-    The FT-P-01 scenario only consumes `wait_for_outbound`, but
-    `get_observer` still requires a valid observer fixture for
-    construction. Populate with safe defaults; per-scenario tests that
-    care about `read_gps_state` carry their own observer fixtures.
-    """
-    payload = {
-        "gps_state": {
-            "primary_source": "MAV",
-            "last_position_lat_deg": 0.0,
-            "last_position_lon_deg": 0.0,
-            "last_position_alt_m": 0.0,
-            "fix_quality": 3,
-            "horizontal_accuracy_m": 1.0,
-            "last_update_age_ms": 0,
-        },
-        "parameters": {},
-    }
-    output_path.parent.mkdir(parents=True, exist_ok=True)
-    output_path.write_text(json.dumps(payload, indent=2))
+# `write_observer_fixture` is re-exported from `_common.py` (used by both b78 + b79).
 
 
 # Orchestration