[AZ-654] [AZ-655] [AZ-656] gimbal_controller primitives + monotonic clock fix (batch 11)

AZ-654 SweepEngine: pendulum default, Raster/LawnMower variants
reserved and explicitly NotImplemented (no silent fallback per AC-3).
Time injected via next_step(now) for deterministic dwell tests.

AZ-655 PlanExecutor: linear yaw/pitch interpolation between PanGoals
with self-throttle (default 50 ms); stats expose
commands_emitted/dropped_to_throttle counters. PanGoal/PanPlan added
to shared::models::gimbal (spec drift: data_model.md §PanPlan flagged
for next doc sync).

AZ-656 CentreOnTarget: zoom-aware proportional control loop (correction
~ 1/zoom); target_lost debounced — fires once per loss streak, resets
on bbox return. Also fixes the misleadingly-named monotonic_ns() helper
introduced by AZ-653 that used SystemTime::now(): GimbalController now
owns a shared::clock::MonoClock and stamps GimbalState::ts_monotonic_ns
via clock.elapsed_ns(). AZ-656 AC-2 forced the correction; integration
test verifies the fix end-to-end.

58/58 gimbal_controller tests green (47 unit + 7 AZ-653 integration +
4 new batch_11 integration). Workspace test suite green this run.

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

_docs/_autodev_state.md

@@ -6,9 +6,9 @@ step: 7
 name: Implement
 status: in_progress
 sub_step:
-  phase: 11
+  phase: 17
   name: tracker-update-in-testing
-  detail: "batch 10 (AZ-653) committed; awaiting In Testing + push"
+  detail: "batch 11 (AZ-654/655/656) committed; awaiting In Testing + push"
 retry_count: 0
 cycle: 1
 tracker: jira