[AZ-626] Decompose complete: 47 tasks + docs + module layout

Greenfield Steps 1-6 baseline for the autopilot rewrite from legacy
Qt/C++ to a Rust workspace.

- Remove legacy Qt/C++ tree (ai_controller, drone_controller,
  misc/camera, python_scaffold, root Dockerfile, autopilot.pro,
  legacy main.py / requirements.txt).
- Add _docs/00_problem (problem, restrictions, acceptance criteria,
  security approach, input data + fixtures).
- Add _docs/01_solution/solution_draft01.
- Add _docs/02_document (architecture, system-flows, data_model,
  glossary, decision-rationale, deployment, 13 component descriptions,
  tests/ specs, FINAL_report, module-layout).
- Add _docs/02_tasks/todo with 47 task specs (AZ-640..AZ-686, one
  bootstrap + 46 component tasks) and _dependencies_table.md.
- Add .cursor/rules/artifact-srp.mdc (single-responsibility rule for
  canonical _docs artifacts).
- Track autodev state in _docs/_autodev_state.md (Step 6 completed,
  ready for Step 7 Implement).

Jira: bootstrap AZ-626; component epics AZ-627..AZ-639; tasks
AZ-640..AZ-686. Total complexity 173 points across 12 epics.

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

_docs/02_document/components/detection_client/description.md

@@ -0,0 +1,76 @@
+# Component — `detection_client`
+
+**Layer**: Perception (data plane in)
+**Status**: forward-looking design (Rust)
+
+## 1. Purpose
+
+Bi-directional gRPC client to the external `../detections` service. Streams frames out, receives bounding-box detections back. Same bboxes are reused by `semantic_analyzer` (Tier 2 ROI selection) and by `telemetry_stream` (operator overlay). This is the only component in autopilot that talks to `../detections`.
+
+## 2. Inputs
+
+| Input | Source | Cadence | Notes |
+|---|---|---|---|
+| `Frame` | `frame_ingest` | up to 30 fps | Skipped when `ai_locked` is set. |
+| Tier-1 service config | startup config | once | gRPC endpoint, TLS settings, request budget, max concurrent streams. |
+
+## 3. Outputs
+
+| Output | Consumer | Shape |
+|---|---|---|
+| `DetectionBatch` | `scan_controller`, `semantic_analyzer`, `telemetry_stream` | `{ frame_seq: u64, detections: Vec<Detection>, latency_ms, model_version }` |
+| Health metric | health aggregator | gRPC connection state, `requests_in_flight`, `latency_p50/p99`, `errors_by_kind`, `model_version`. |
+
+`Detection` mirrors the `../detections` contract: `{ class_id, class_name, confidence, bbox_normalized, optional_mask_or_polyline, source_frame_seq }`.
+
+## 4. Key Responsibilities
+
+- Maintain a single bi-directional gRPC stream to `../detections`. Reconnect on stream loss with bounded exponential backoff.
+- Frame budgeting: respect the Tier-1 ≤100 ms/frame target by dropping older in-flight frames if a new frame arrives before the previous response (configurable).
+- Validate the response payload against the schema version the client was built against. Surface a hard error on schema mismatch; do not silently downcast.
+- Tag each `DetectionBatch` with the source frame's monotonic timestamp so downstream consumers can compute end-to-end latency.
+
+## 5. Internal State
+
+- gRPC channel, stream handle, reconnect state.
+- Sliding window of in-flight frame sequence numbers.
+- Last-known model version (echoed by `../detections` on each response or on stream init).
+
+State is in-process only.
+
+## 6. Failure Modes
+
+| Failure | Detection | Behaviour |
+|---|---|---|
+| `../detections` unreachable | gRPC connect error | Bounded exponential backoff; health → red after threshold; `scan_controller` continues but the `detection_client` health flag is red. |
+| Mid-stream cancellation by server | stream error | Reopen stream; do not lose frames in flight (best-effort retry on the latest only). |
+| Schema mismatch | response decode error | Hard error to the health aggregator; reject the response; alert. |
+| Model version change at runtime | new `model_version` on the stream | Log it; if the change implies new classes, surface to `scan_controller` so per-class thresholds can be reloaded. |
+| Consistent latency above budget | `latency_p99 > 100 ms` over a sliding window | Health → yellow; `scan_controller` may degrade to alternate-frame inference. |
+
+## 7. Dependencies
+
+**In-process**: `frame_ingest` (input), `scan_controller` / `semantic_analyzer` / `telemetry_stream` (output).
+
+**External**:
+- `../detections` gRPC service. Contract owner: `../_docs/03_detections.md`. Bi-directional streaming.
+
+## 8. Non-Functional Targets
+
+| Concern | Target |
+|---|---|
+| Per-frame round-trip latency | ≤100 ms (Tier-1 NFR; mostly owned by `../detections`, autopilot's call budget respects it) |
+| Reconnect latency | ≤2 s after `../detections` returns |
+| Throughput | up to 30 fps at 1080p |
+| Backpressure | drop oldest in-flight rather than queue indefinitely |
+
+## 9. Open Questions
+
+- Versioning strategy of the gRPC contract (covered in `architecture.md §8 Q4`).
+
+## 10. References
+
+- `architecture.md §1`, `§3`, `§7.6`.
+- `system-flows.md §F1`.
+- `../_docs/03_detections.md`.
+- `data_model.md §Detection`, `§DetectionBatch`.