[AZ-645] [AZ-646] [AZ-647] mission_client: middle-waypoint POST + mapobjects pull/push

Batch 3 of greenfield Step 7 — mission_client epic AZ-638 close-out.

AZ-645 (Middle-waypoint POST)
- post_middle_waypoint(mission_id, &Mission) -> Result<MissionUpdateAck, PostError>
- Bounded retry (default 3 attempts) shared with the rest of missions_api
- Health: last_middle_waypoint_post_status (ok/error)

AZ-646 (Pre-flight MapObjects pull)
- pull_mapobjects(mission_id) -> Result<MapObjectsBundle, PullError>
- Schema-validated against bundled shared/contracts/mapobjects-bundle.json
- Typed errors: Unreachable / SchemaInvalid / MaxRetriesExceeded / Internal
- Health: mapobjects_pull_state, last_mapobjects_pull_ts

AZ-647 (Post-flight push + durable disk queue)
- push_mapobjects_diff(mission_id, MapObjectsDiff) -> PushReport
- recover_pending_pushes() -> Vec<PushReport> for crash recovery
- Write-ahead atomic-rename persistence under ${state_dir}/mapobjects_push/
- Per-endpoint independent retry: observations + ignored_items
- Partial success rewrites the disk file with only the failing portion
- Health: mapobjects_push_pending, last_push_ts, per-endpoint last error

Infrastructure
- Schemas: shared/contracts/mapobjects-{bundle,observations,ignored}.json
- Restructured schema/ into mission.rs + mapobjects.rs sub-modules
- New mapobjects_sync/ (pull, push, queue)
- workspace dep tempfile=3; mission_client dev-deps add tempfile + chrono

Tests
- 12/12 ACs verified locally (4 AZ-645 + 4 AZ-646 + 5 AZ-647)
- mission_client suite: 15 unit + 18 integration = 33 tests pass
- AZ-646 AC-4 proxy: 1000-object + 1000-ignored bundle within 30s
- AZ-647 AC-5 proxy: 5000-obs + 500-ignored push within 2min

Code review verdict: PASS_WITH_WARNINGS (inline). Cumulative review
(K=3 trigger) PASS_WITH_WARNINGS — full report in
_docs/03_implementation/cumulative_review_batches_01-03_cycle1_report.md.

Open follow-ups (non-blocking):
- module-layout.md: rename push_mapobjects -> push_mapobjects_diff (Step 13)
- ExponentialBackoff still duplicated across crates; promote to shared::retry
  when the third caller lands (likely detection_client AZ-660/661)
- state_dir default is relative; composition root must override

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

Cargo.toml

@@ -64,6 +64,7 @@ tokio-serial = "5"
 
 # Test scaffolding
 wiremock = "0.6"
+tempfile = "3"
 
 # Workspace-internal
 shared = { path = "crates/shared" }