[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/movement_detector/description.md

@@ -0,0 +1,96 @@
+# Component — `movement_detector`
+
+**Layer**: Perception (data plane in)
+**Status**: forward-looking design (Rust + OpenCV bindings; learned-CV fallback per `architecture.md §8 Q14`)
+
+## 1. Purpose
+
+Detect small moving point/cluster candidates that are not yet classifiable by Tier 1, in **both** the zoom-out and zoom-in scan levels, and enqueue them as POIs for confirmation. Compensates for UAV and gimbal motion using synchronised telemetry; naive frame differencing is rejected.
+
+The component is suppressed only during `scan_controller`'s `TargetFollow` state (the gimbal is dominated by tracking commands during follow).
+
+## 2. Inputs
+
+| Input | Source | Cadence | Notes |
+|---|---|---|---|
+| `Frame` | `frame_ingest` | up to 30 fps | Frames are skipped when `ai_locked` is set or the system is in `TargetFollow`. |
+| Gimbal angle (yaw, pitch) | `gimbal_controller` | per frame, monotonic-timestamped | Telemetry-skew gate: reject samples where frame ↔ gimbal skew exceeds the configured tolerance for the current zoom band. |
+| Zoom state | `gimbal_controller` | per frame, monotonic-timestamped | Drives zoom-band selection (`zoomed_out` vs `zoomed_in`) and per-band thresholds; also used for residual-motion scaling. |
+| UAV motion telemetry | `mavlink_layer` (via `mission_executor`) | 10 Hz target | Position + attitude + velocity + monotonic timestamp. |
+| Active-state hint | `scan_controller` | event | `enable_zoomed_out` / `enable_zoomed_in` / `disable` (the latter is set during `TargetFollow`). |
+
+## 3. Outputs
+
+| Output | Consumer | Shape |
+|---|---|---|
+| `MovementCandidate` | `scan_controller` | `{ frame_seq, bbox_normalized, residual_velocity_estimate, telemetry_quality, source_frame_ts, source_zoom_band }` |
+| Health metric | health aggregator | `enabled`, `current_zoom_band`, `candidates_per_min_zoomed_out`, `candidates_per_min_zoomed_in`, `telemetry_skew_drops_total`, `compensation_quality_per_band`. |
+
+## 4. Key Responsibilities
+
+- Compute per-frame ego-motion using OpenCV optical flow / global motion estimation (e.g. dense Lucas-Kanade or feature-based homography), refined by the synchronised gimbal + UAV telemetry.
+- Subtract estimated ego-motion from per-pixel motion; cluster the residuals.
+- Emit clusters that meet the **per-zoom-band** minimum size + persistence threshold as `MovementCandidate`s, capped to honour the system-wide ≤5 POIs/min operator-review budget shared with `scan_controller`.
+- Self-disable in `TargetFollow`. The component still consumes frames while disabled (to keep its motion-history warm) but emits no candidates.
+- Tag each emitted candidate with `source_zoom_band` so `scan_controller` can apply zoom-band-aware queueing logic (described in `system-flows.md §F2`).
+
+## 5. Per-zoom-band tuning
+
+The same code path runs at zoom-out and zoom-in, but the configuration differs because the pixel-to-metre ratio differs by ~10×.
+
+| Knob | Zoom-out (typical) | Zoom-in (typical) |
+|---|---|---|
+| Cluster persistence threshold | 3–5 frames | 6–10 frames (gimbal-pan-induced flicker is more frequent at narrow FOV) |
+| Residual-velocity floor | low (small physical motion is enough) | higher (small physical motion is amplified pixel-wise; raising the floor reduces FP from compensation residuals) |
+| Telemetry-skew tolerance | 50 ms frame ↔ gimbal, 100 ms frame ↔ UAV | 25 ms frame ↔ gimbal, 50 ms frame ↔ UAV (stricter — gimbal slewing dominates zoomed FOV) |
+| Enqueue-latency budget | ≤1 s | ≤1.5 s (allows brief gimbal-stability window) |
+| FP cap (per-band) | per `architecture.md §6 NFR` | per `architecture.md §6 NFR`; if exceeded, fallback per Q14 |
+
+Exact values are mission-tunable; defaults are calibrated during the benchmark gate.
+
+## 6. Internal State
+
+- Rolling motion-history buffer (a few seconds of frames + telemetry). One buffer per zoom band; switching bands does not invalidate the buffer for the other.
+- Per-cluster persistence counters (per zoom band).
+- Telemetry-sync state machine.
+- `current_zoom_band` derived from `gimbal_controller`'s zoom state.
+
+State is in-process only.
+
+## 7. Failure Modes
+
+| Failure | Detection | Behaviour |
+|---|---|---|
+| Telemetry skew above tolerance (per zoom band) | timestamp delta exceeds threshold | Drop that frame's compensation; do not emit candidates for the affected window; counter-tagged drop. |
+| Optical-flow degenerate | flow magnitudes implausible (e.g. camera failure, full motion blur) | Skip emission for that frame; surface as a health signal on sustained occurrence. |
+| Sustained candidate flood at zoom-in (FP cap exceeded) | candidates_per_min_zoomed_in over a sliding window | Suppress zoom-in emission only; keep zoom-out emission running; surface health → yellow; this is the trigger condition for the Q14 fallback. |
+| Sustained candidate flood at zoom-out (FP cap exceeded) | candidates_per_min_zoomed_out over a sliding window | Down-rank lowest-confidence candidates; surface health → yellow; never silently drop without counting. |
+| Component disabled by `scan_controller` | active-state hint = `disable` | Emit zero candidates; keep motion history warm. |
+
+## 8. Dependencies
+
+**In-process**: `frame_ingest`, `gimbal_controller`, `mavlink_layer`, `scan_controller`.
+
+**External**: OpenCV (patched, version-pinned). Optional: a learned-CV crate / module (RAFT-derivative or CNN motion-segmentation) behind a build-time feature flag — engaged only when the Q14 fallback is required.
+
+## 9. Non-Functional Targets
+
+| Concern | Target |
+|---|---|
+| Candidate enqueue latency (zoom-out) | ≤1 s from detection to POI in queue |
+| Candidate enqueue latency (zoom-in) | ≤1.5 s from detection to POI in queue |
+| False-positive rate at the operator surface | bounded by `scan_controller`'s ≤5 POIs/min cap; per-zoom-band internal caps prevent zoom-in starving zoom-out |
+| CPU budget on Jetson | configurable; must coexist with Tier 1 (running in `../detections`) and Tier 2 |
+| Telemetry-skew tolerance | per-zoom-band; defaults in §5 |
+
+## 10. Open Questions
+
+- **Q14 fallback selection** (architecture.md §8): if classical OpenCV fails the per-zoom-band FP cap at zoom-in, the fallback module — learned optical flow vs CNN motion-segmentation vs IMU-tighter-coupled classical — is open. Interface contract is fixed (`Frame + telemetry → Vec<MovementCandidate>`).
+- Minimum cluster persistence threshold across zoom bands (refined during benchmark gate).
+- Whether to share the motion-history buffer across zoom-band transitions or reset on transition (§6 currently says share).
+
+## 11. References
+
+- `architecture.md §3`, `§5 Architectural Principles` (ego-motion compensation mandatory; movement runs at both zoom levels), `§7.6 Movement detector`, `§8 Q14`.
+- `system-flows.md §F2 Movement detection (zoom-out + zoom-in)`.
+- `data_model.md §MovementCandidate`.