[AZ-640] Bootstrap Rust workspace, CI/Docker, observability scaffold

Lands the first task of the implementation epic AZ-626: a cargo workspace
with 14 crates (shared + autopilot binary + 12 component crates), a
multi-stage Dockerfile + dev/test compose stacks, a Woodpecker CI pipeline,
the on-airframe systemd unit with flight-gate wiring, three environment
TOML configs, and the canonical entity catalogue from data_model.md as
`shared::models`.

Per-AC verification (full detail in
_docs/03_implementation/batch_01_cycle1_report.md):

- AC-1 cargo check --workspace clean
- AC-2 cargo test --workspace passes; per-crate it_compiles() <0.01 s
- AC-6 cargo build/test --no-default-features clean; VlmClient default
       impl returns VlmAssessment::disabled()
- AC-9 tracing-subscriber emits JSON logs with ts/level/target/fields
- AC-10 runtime::ensure_state_directories creates mapobjects/, audit/,
        pending_pushes/ under storage.state_dir

Deferred to external infra (artifacts written, verification re-runs in CI
and in downstream tasks):
- AC-3 Woodpecker runner; CI yml in place
- AC-4 docker-compose mocks land with AZ-660/AZ-644/AZ-675
- AC-5 SITL conformance lands with AZ-641/AZ-648/AZ-652
- AC-7 aarch64 cross-compile via cargo-zigbuild stage
- AC-8 systemd unit (Linux + systemd host)

Layering invariants from module-layout.md hold: shared (L1) imports
nothing; Layer 2 actor crates import only shared; Layer 3 coordinators
(operator_bridge, mission_executor) import only their documented Layer 2
deps; Layer 4 (scan_controller) imports its documented Layer 2 + Layer 3
deps; the autopilot binary (L5) is the only consumer of every component.

cargo fmt --all --check + cargo clippy --all-targets -- -D warnings both
clean. Jira AZ-640 transitioned to In Progress at the start of this batch;
the matching In Testing transition follows this commit.

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

crates/gimbal_controller/src/lib.rs

@@ -0,0 +1,89 @@
+//! `gimbal_controller` — ViewPro A40 UDP control + smooth-pan primitive.
+//!
+//! Real implementation lands in:
+//! - AZ-653 `gimbal_a40_transport`
+//! - AZ-654 `gimbal_zoom_out_sweep`
+//! - AZ-655 `gimbal_smooth_pan_plan`
+//! - AZ-656 `gimbal_centre_on_target`
+
+use serde::{Deserialize, Serialize};
+use tokio::sync::watch;
+
+use shared::error::{AutopilotError, Result};
+use shared::health::ComponentHealth;
+use shared::models::gimbal::GimbalState;
+
+const NAME: &str = "gimbal_controller";
+
+#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
+pub struct GimbalCommand {
+    pub yaw_deg: f32,
+    pub pitch_deg: f32,
+}
+
+pub struct GimbalController {
+    state_tx: watch::Sender<GimbalState>,
+}
+
+impl GimbalController {
+    pub fn new(initial: GimbalState) -> Self {
+        let (state_tx, _rx) = watch::channel(initial);
+        Self { state_tx }
+    }
+
+    pub fn handle(&self) -> GimbalControllerHandle {
+        GimbalControllerHandle {
+            state_tx: self.state_tx.clone(),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct GimbalControllerHandle {
+    state_tx: watch::Sender<GimbalState>,
+}
+
+impl GimbalControllerHandle {
+    pub async fn set_pose(&self, _command: GimbalCommand) -> Result<()> {
+        Err(AutopilotError::NotImplemented(
+            "gimbal_controller::set_pose (AZ-653)",
+        ))
+    }
+
+    pub async fn zoom(&self, _level: f32) -> Result<()> {
+        Err(AutopilotError::NotImplemented(
+            "gimbal_controller::zoom (AZ-654)",
+        ))
+    }
+
+    pub fn state(&self) -> GimbalState {
+        *self.state_tx.borrow()
+    }
+
+    pub fn state_stream(&self) -> watch::Receiver<GimbalState> {
+        self.state_tx.subscribe()
+    }
+
+    pub fn health(&self) -> ComponentHealth {
+        ComponentHealth::disabled(NAME)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_compiles() {
+        let initial = GimbalState {
+            yaw: 0.0,
+            pitch: 0.0,
+            zoom: 1.0,
+            ts_monotonic_ns: 0,
+            command_in_flight: false,
+        };
+        let h = GimbalController::new(initial).handle();
+        assert_eq!(h.state().zoom, 1.0);
+        assert_eq!(h.health().level, shared::health::HealthLevel::Disabled);
+    }
+}