[AZ-270] [AZ-272] [AZ-279] [AZ-281] [AZ-283] Compose root + FDR schema + 3 Layer-1 helpers

AZ-270: composition root with strategy registry, tier-gated lookup,
topo-order construction, all-or-nothing teardown, StrategyNotLinkedError
payload.
AZ-272: orjson-backed FdrRecord serialise/parse with forward-compat for
unknown payload + top-level fields and canonical overrun-record shape.
AZ-279: pyproj-backed WGS84/ECEF/ENU + OSM slippy-map tile math with
WgsConversionError for shape/range/zoom guards.
AZ-281: strict EngineFilenameSchema build/parse/matches_host with
anchored regex + enum validation; round-trip identity by construction.
AZ-283: dtype-preserving (fp16/fp32) single + batch L2 normaliser with
zero-norm safety and descriptor_metric() source-of-truth.
pyproject.toml pins pyproj>=3.6 and orjson>=3.9 (named-backend deps per
the AZ-272 / AZ-279 contracts). New DTOs LatLonAlt + BoundingBox and
EngineCacheKey + HostCapabilities land in _types/ to back the helper
contracts.
203 unit tests pass (64 new). Review verdict: PASS_WITH_WARNINGS;
findings are perf-NFR deferrals + dep amendment + minor docstring polish.

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

src/gps_denied_onboard/helpers/__init__.py

@@ -5,6 +5,17 @@ ones that have landed so consumers can depend on a stable public surface
 without reaching into the helper modules directly.
 """
 
+from gps_denied_onboard.helpers.descriptor_normaliser import (
+    ALLOWED_DTYPES,
+    DescriptorNormaliser,
+    DescriptorNormaliserError,
+)
+from gps_denied_onboard.helpers.engine_filename_schema import (
+    ALLOWED_PRECISIONS,
+    ENGINE_SUFFIX,
+    EngineFilenameSchema,
+    EngineFilenameSchemaError,
+)
 from gps_denied_onboard.helpers.se3_utils import (
     SE3,
     Se3InvalidMatrixError,
@@ -20,13 +31,30 @@ from gps_denied_onboard.helpers.sha256_sidecar import (
     Sha256Sidecar,
     Sha256SidecarError,
 )
+from gps_denied_onboard.helpers.wgs_converter import (
+    MAX_ZOOM,
+    WEB_MERCATOR_MAX_LAT_DEG,
+    WgsConversionError,
+    WgsConverter,
+)
 
 __all__ = [
+    "ALLOWED_DTYPES",
+    "ALLOWED_PRECISIONS",
+    "ENGINE_SUFFIX",
+    "MAX_ZOOM",
     "SE3",
     "SIDECAR_SUFFIX",
+    "WEB_MERCATOR_MAX_LAT_DEG",
+    "DescriptorNormaliser",
+    "DescriptorNormaliserError",
+    "EngineFilenameSchema",
+    "EngineFilenameSchemaError",
     "Se3InvalidMatrixError",
     "Sha256Sidecar",
     "Sha256SidecarError",
+    "WgsConversionError",
+    "WgsConverter",
     "adjoint",
     "exp_map",
     "is_valid_rotation",