Basic UI Shell: bring back the in-game flight HUD and station info panel,
and implement the missing "station mode panel swap."
Implementation:
- New `in_system/hud.rs` with a reactive, idempotent `sync_hud_panels`
system: it shows the station info panel while the player is `Docked` and
the flight HUD while in `FlightState`, spawning/despawning only when the
on-screen panel disagrees with the player's state. This replaces the old
fragile event-driven spawn/despawn scattered through the transition systems.
- Re-enabled the docked info panel (`ui.rs`) and flight HUD (`flight_ui.rs`),
restructured both as small corner-anchored overlays with NO full-screen
root so they only block camera orbit input when the cursor is directly
over a panel (orbit_camera_control suppresses input over any UI node).
- Made the docked panel info-only (actions live in the contextual action
panel, which adapts to docked/flight modes).
- Fixed the broken undock chain: `start_undocking`/`start_travel` now take a
real `now_ms` (was hardcoded `0.0`, completing instantly) and a new
`complete_operations` bridge maps `OperationCompletedEvent::Undocking`
back to `UndockEvent` so `handle_undock` actually runs.
- Wired `ActionType::Dock` to fire a `DockEvent` for a targeted station /
habitable planet so the flight→docked swap is reachable too.
- `handle_docking` now also clears Velocity/MoveTarget/SelectedTarget so the
docked ship stops cleanly.
- Fixed deprecated Bevy 0.16 APIs (single_mut, EventWriter::write,
despawn) and removed now-dead code, dropping total warnings 183→137.
Compiles clean (`cargo check`); no new warnings in touched files.
francy51
7b9b892bfb