[AZ-263] Bootstrap: repo skeleton + Docker + CI + Alembic + Tier-1 tests

Implements the AZ-263 / E-BOOT initial structure task:

- Python src/-layout package `gps_denied_onboard/` with per-component
  interface stubs (14 components), type-only DTOs under `_types/`,
  shared helpers under `helpers/` (R14 LightGlue ownership), structured
  JSON logging, runtime composition root with env-var fail-fast gate,
  healthcheck module shared by Docker and CI smoke.
- CMake top-level + `cmake/{build_options,dependencies,strategies}.cmake`
  with the BUILD_* per-binary flags (ADR-002) and pinned external git
  refs for OKVIS2 / VINS-Mono / GTSAM / FAISS / OpenCV >=4.12.0.
- Three Dockerfiles (companion-tier1, operator-tooling,
  mock-suite-sat-service) + two compose files (dev + Tier-1 test).
- Four GitHub Actions workflows: ci.yml (lint/unit/integration/dual
  binary build/SBOM diff/security), ci-tier2.yml (self-hosted Jetson
  AC-bound NFTs), release.yml, cve-rescan.yml.
- Two CI gate scripts: `ci/sbom_diff.py` (deployment SBOM subset +
  R02 exclusion), `ci/opencv_pin_gate.py` (>=4.12.0 enforcement,
  D-CROSS-CVE-1).
- Alembic-driven Postgres 16 initial migration `0001_initial.py`
  mirroring satellite-provider tiles + flights + sector_classifications
  + manifests + engine_cache_entries (data_model.md s 2).
- Tier-1 test scaffolding: 95 passing unit tests covering every AC,
  per-component smoke tests, structured logging JSON output check,
  env-var gate check, healthcheck import check. Two CI-gated tests
  (cmake configure, actionlint) skip locally with explicit reasons.
- Batch report + code review report under `_docs/03_implementation/`.

Verdict: PASS_WITH_WARNINGS (two Low findings, both informational).
Co-authored-by: Cursor <cursoragent@cursor.com>

src/gps_denied_onboard/components/c5_state/__init__.py

@@ -0,0 +1,6 @@
+"""C5 State Estimator component — Public API."""
+
+from gps_denied_onboard._types.pose import EstimatorHealth, EstimatorOutput
+from gps_denied_onboard.components.c5_state.interface import StateEstimator
+
+__all__ = ["EstimatorHealth", "EstimatorOutput", "StateEstimator"]

src/gps_denied_onboard/components/c5_state/_native/__init__.py

@@ -0,0 +1 @@
+"""pybind11 wrapper for `cpp/gtsam_bindings/` (primary owner; also used READ-ONLY by c4_pose)."""

src/gps_denied_onboard/components/c5_state/interface.py

@@ -0,0 +1,23 @@
+"""C5 `StateEstimator` Protocol.
+
+Concrete impls: `GtsamIsam2StateEstimator` (production-default; iSAM2 +
+IncrementalFixedLagSmoother), `EskfStateEstimator` (mandatory simple baseline).
+See `_docs/02_document/components/07_c5_state/`.
+"""
+
+from __future__ import annotations
+
+from typing import Protocol
+
+from gps_denied_onboard._types.pose import EstimatorOutput, PoseEstimate
+from gps_denied_onboard._types.vio import VioOutput
+
+
+class StateEstimator(Protocol):
+    """Smoothed state estimator (fuses VIO + satellite anchors + IMU)."""
+
+    def add_vio(self, vio: VioOutput) -> None: ...
+
+    def add_pose_anchor(self, anchor: PoseEstimate) -> None: ...
+
+    def latest_output(self) -> EstimatorOutput | None: ...