[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/gimbal_controller/description.md

@@ -0,0 +1,78 @@
+# Component — `gimbal_controller`
+
+**Layer**: Action (data plane out)
+**Status**: forward-looking design (Rust); ViewPro A40 vendor protocol
+
+## 1. Purpose
+
+Drives the ViewPro A40 gimbal: pan (yaw), tilt (pitch), and zoom. Honours the ≤2 s zoom-transition budget and ≤500 ms decision-to-movement latency. Owns the zoom-out sweep, the smooth-pan path-tracking primitive used during the zoom-in level (follow-the-footpath behaviour), and the centre-window primitive used during target-follow.
+
+## 2. Inputs
+
+| Input | Source | Cadence | Notes |
+|---|---|---|---|
+| `GimbalCommand` | `scan_controller` | per state-machine tick or per zoom-in plan step | yaw / pitch / zoom goal; or pan plan; or centre-on-target. |
+| Sweep config | startup config | once | Zoom-out sweep pattern (pendulum / raster / lawn-mower — see `architecture.md §8 Q1`). |
+| Live gimbal status | ViewPro A40 (vendor protocol) | as emitted by camera | yaw / pitch / zoom feedback + faults. |
+
+## 3. Outputs
+
+| Output | Consumer | Shape |
+|---|---|---|
+| Vendor-protocol commands | ViewPro A40 (UDP) | yaw / pitch / zoom commands |
+| `GimbalState` | `frame_ingest` (for telemetry tagging), `movement_detector` (for ego-motion compensation) | `{ yaw, pitch, zoom, ts_monotonic, command_in_flight: bool }` |
+| Health metric | health aggregator | `commands_per_min`, `decision_to_movement_p99_ms`, `zoom_transition_p99_ms`, `vendor_faults_total`. |
+
+## 4. Key Responsibilities
+
+- Send vendor-protocol commands to the ViewPro A40 over UDP. Re-issue on timeout with bounded retry.
+- Run the zoom-out sweep pattern when `scan_controller` is in `ZoomedOut` (pattern itself depends on `architecture.md §8 Q1` resolution).
+- For the zoom-in path-follow, accept a pan plan (sequence of yaw / pitch / zoom goals with timing) from `scan_controller` / `semantic_analyzer` and execute it smoothly.
+- For target-follow, accept a centre-on-target stream (target bbox normalized) from `scan_controller` and command the gimbal to keep the target inside the centre 25 % of frame while visible.
+- Stamp every emitted command with a monotonic timestamp so `movement_detector` can synchronise it with frames.
+- Surface vendor-protocol faults to health and to `scan_controller`.
+
+## 5. Internal State
+
+- Last-known commanded yaw / pitch / zoom.
+- Last-known reported yaw / pitch / zoom (from gimbal feedback).
+- Sweep pattern state (current direction, dwell counter).
+- Current execution mode: `Sweep | PanPlan | CentreOnTarget | Idle`.
+
+State is in-process only.
+
+## 6. Failure Modes
+
+| Failure | Detection | Behaviour |
+|---|---|---|
+| ViewPro A40 not responding | command timeout | Bounded exponential backoff; health → yellow then red; `scan_controller` is informed and may pause zoom-in. |
+| Decision-to-movement above budget | self-instrumented | Health → yellow; investigate (likely UDP loss or vendor firmware issue). |
+| Zoom transition stalls | feedback shows no zoom progress | Re-issue command; health → yellow; report to `scan_controller`. |
+| Target lost during target-follow | feedback + tracker | Surface `target_lost` to `scan_controller`; controller decides to release follow. |
+| Conflicting commands | execution-mode mismatch | Reject the lower-priority command; log a hard error; never silently merge. |
+
+## 7. Dependencies
+
+**In-process** (input): `scan_controller`.
+**In-process** (output): `frame_ingest`, `movement_detector` (timestamped state).
+
+**External**: ViewPro A40 over UDP (vendor protocol).
+
+## 8. Non-Functional Targets
+
+| Concern | Target |
+|---|---|
+| Decision-to-movement latency | ≤500 ms |
+| Zoom transition (medium → high) | ≤2 s |
+| Sweep pattern stability | bounded jitter; no overshoot beyond configured FOV bounds |
+| Target-follow centre-window | target inside centre 25 % of frame while visible |
+
+## 9. Open Questions
+
+- Sweep pattern specification (`architecture.md §8 Q1`): pendulum / raster / lawn-mower; FOV per zoom tier; dwell time per direction.
+
+## 10. References
+
+- `architecture.md §3`, `§6 NFR`, `§7.6 Solution Architecture`.
+- `system-flows.md §F2 Movement detection (zoom-out + zoom-in)`.
+- `data_model.md §GimbalState`.