[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.lock

@@ -470,6 +470,12 @@ dependencies = [
  "regex-syntax",
 ]
 
+[[package]]
+name = "fastrand"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6"
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
@@ -1056,6 +1062,12 @@ version = "0.2.186"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
+
 [[package]]
 name = "litemap"
 version = "0.8.2"
@@ -1182,11 +1194,13 @@ dependencies = [
 name = "mission_client"
 version = "0.1.0"
 dependencies = [
+ "chrono",
  "jsonschema",
  "reqwest",
  "serde",
  "serde_json",
  "shared",
+ "tempfile",
  "thiserror 1.0.69",
  "tokio",
  "tracing",
@@ -1655,6 +1669,19 @@ version = "2.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94300abf3f1ae2e2b8ffb7b58043de3d399c73fa6f4b73826402a5c457614dbe"
 
+[[package]]
+name = "rustix"
+version = "1.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6fe4565b9518b83ef4f91bb47ce29620ca828bd32cb7e408f0062e9930ba190"
+dependencies = [
+ "bitflags 2.11.1",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "rustls"
 version = "0.23.40"
@@ -1970,6 +1997,19 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.27.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
+dependencies = [
+ "fastrand",
+ "getrandom 0.4.2",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"