[AZ-701] HTTP replay API service (FastAPI + magic-byte upload validation)

New replay_api component: FastAPI service wrapping the offline
gps-denied-replay pipeline. POST tlog+video (multipart) → either
sync 200 with result/map/report URLs, or async 202 + job id with
/jobs/{id} polling. Magic-byte validation, bearer auth, in-memory
JobRegistry with concurrency + queue caps (429 on overflow).

Helper accuracy_report.py promoted from tests/ to src/ because the
API needs the Markdown report writer at runtime; all AZ-699 imports
re-pointed. OpenAPI spec exported to docs.

18/18 unit tests pass (AC-1 sync, AC-2 async, AC-3 state machine,
AC-5 auth, AC-6 health, AC-8 concurrency, AC-9 magic-byte). Full
unit suite: 2251 pass, 86 skip, 1 pre-existing C12 cold-start flake
(unchanged). mypy --strict clean on the new surface.

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

src/gps_denied_onboard/replay_api/errors.py

@@ -0,0 +1,86 @@
+"""AZ-701 — typed HTTP error families for the replay_api service.
+
+Every error has a stable ``error_code`` (string) the contract pins
+in ``_docs/02_document/contracts/replay_api/replay_api_protocol.md``.
+The handler layer translates these into JSON responses; the
+business layer raises them without knowing about HTTP.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+__all__ = [
+    "ConcurrencyLimitReachedError",
+    "JobNotCompleteError",
+    "JobNotFoundError",
+    "MultipartMissingFieldError",
+    "PayloadTooLargeError",
+    "ReplayApiError",
+    "ReplayRunnerError",
+    "UnauthorizedError",
+    "UnsupportedFileKindError",
+]
+
+
+class ReplayApiError(Exception):
+    """Base for every typed replay_api error.
+
+    Subclasses pin a stable ``error_code`` and HTTP ``status_code``;
+    the handler layer reads both to build a JSON response.
+    """
+
+    error_code: str = "replay_api_error"
+    status_code: int = 500
+
+    def __init__(self, message: str, details: dict[str, Any] | None = None) -> None:
+        super().__init__(message)
+        self.message = message
+        self.details = details or {}
+
+
+class UnsupportedFileKindError(ReplayApiError):
+    error_code = "unsupported_file_kind"
+    status_code = 400
+
+
+class MultipartMissingFieldError(ReplayApiError):
+    error_code = "multipart_missing_field"
+    status_code = 400
+
+
+class UnauthorizedError(ReplayApiError):
+    error_code = "unauthorized"
+    status_code = 401
+
+
+class JobNotFoundError(ReplayApiError):
+    error_code = "job_not_found"
+    status_code = 404
+
+
+class JobNotCompleteError(ReplayApiError):
+    error_code = "job_not_complete"
+    status_code = 409
+
+
+class PayloadTooLargeError(ReplayApiError):
+    error_code = "payload_too_large"
+    status_code = 413
+
+
+class ConcurrencyLimitReachedError(ReplayApiError):
+    """Raised when the queue is full.
+
+    Note: per-spec, hitting just the running-job concurrency limit
+    does NOT raise this — those jobs queue normally. The 429 case is
+    "queue itself is full" only.
+    """
+
+    error_code = "concurrency_limit_reached"
+    status_code = 429
+
+
+class ReplayRunnerError(ReplayApiError):
+    error_code = "replay_runner_failed"
+    status_code = 500