feat(gameplay): implement in-system onboarding with docked station view

Implement the final onboarding step where the player loads into their
selected starting system docked at a station.

New features:
- Create in_system module for system-scale gameplay
- Spawn player ship docked at highest-population station
- Display station info panel with undock button
- Position camera for cinematic docked view with orbit controls

Implementation details:
- in_system/mod.rs: Plugin setup with DockedState and ActiveSystem resources
- in_system/scene.rs: System/POI spawning and player ship docked positioning
- in_system/docked.rs: Docked state management and UndockEvent
- in_system/ui.rs: Docked UI with station details and undock button
- Reuse existing POI spawning patterns from galaxy/contents.rs
- Select docking station by highest population (better for new players)

Modified files:
- Add in_system module exports to gameplay/mod.rs
- Register InSystemPlugin in main.rs
- Update orbit camera control for InGame state
- Re-export GeneratedStation and STARTING_SHIPS for use by in_system

The player now completes onboarding by loading into a system view with
their ship docked at a station, ready for gameplay.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/game/src/gameplay/starting_base/mod.rs

@@ -9,33 +9,40 @@ mod ui;
 
 use bevy::prelude::*;
 
-use crate::gameplay::galaxy::StartingBaseCandidate;
+use crate::gameplay::galaxy::{StartingBaseCandidate, orbits};
 use crate::state::AppState;
 
+// Public exports for POI spawning
+pub use scene::{SpawnedPoiSystem, StartingBasePoi};
+
 pub struct StartingBasePlugin;
 
 impl Plugin for StartingBasePlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<StartingBaseDraft>()
+            .init_resource::<StartingBaseFocusGoal>()
+            .init_resource::<scene::SpawnedPoiSystem>()
             .add_systems(
                 OnEnter(AppState::StartingBaseSelection),
                 (scene::setup_starting_base_scene, ui::setup_starting_base_ui).chain(),
             )
             .add_systems(
                 OnExit(AppState::StartingBaseSelection),
-                despawn_starting_base_ui,
+                (despawn_starting_base_ui, scene::despawn_pois_on_exit).chain(),
             )
             .add_systems(
                 Update,
                 (
                     escape_to_character_creation,
                     scene::starting_base_orbit_camera_control,
-                    scene::select_starting_base_on_click,
+                    ui::candidate_button_handler,
+                    scene::focus_starting_base_camera,
                     scene::animate_starting_base_selection,
                     ui::scroll_starting_base_panels,
-                    ui::candidate_button_handler,
                     ui::refresh_starting_base_ui,
                     ui::action_button_handler,
+                    scene::spawn_selected_pois,
+                    orbits::advance_orbital_paths,
                 )
                     .chain()
                     .run_if(in_state(AppState::StartingBaseSelection)),
@@ -57,6 +64,27 @@ pub struct StartingBaseSelection {
     pub security: f32,
 }
 
+#[derive(Resource, Debug, Clone, Copy)]
+pub struct StartingBaseFocusRequest {
+    pub candidate_index: usize,
+}
+
+/// Resolved focus target the starting-base camera tweens toward. Set by
+/// [`crate::gameplay::starting_base::scene::focus_starting_base_camera`] when a
+/// candidate is selected, then approached gradually by the orbit control
+/// system, which clears `active` once the camera arrives (or the user takes
+/// manual control by dragging / scrolling).
+///
+/// Persistent rather than inserted/removed on demand so the consumer can mutate
+/// it via a single `ResMut` and keep the orbit control system's parameter count
+/// manageable.
+#[derive(Resource, Debug, Clone, Copy, Default)]
+pub struct StartingBaseFocusGoal {
+    pub target: Vec3,
+    pub distance: f32,
+    pub active: bool,
+}
+
 #[derive(Component)]
 pub struct StartingBaseSpawned;