feat(stage-tamagotchi-godot): camera control (#1855)

## Summary

This PR adds the first usable camera and view-state loop for the
experimental Godot stage.

The main design direction is that Godot owns the stage view state, while
Electron and the settings page act as lifecycle/transport/control
surfaces. The settings UI can now edit Godot camera state, and camera
changes from the Godot window can flow back to the UI.

## What Changed

- Added the shared Godot view-state contract for camera pose, avatar
bounds, snapshots, patches, and errors.
- Added Electron main bridge APIs for Godot status, scene input, view
snapshots, and view patches.
- Added Godot-side camera runtime:
  - initial camera bootstrap from loaded avatar bounds
  - avatar facing normalisation
  - orbit, pan, wheel movement, and WASD-style camera movement
  - idle persistence for camera position, yaw, pitch, and FOV
- Added settings-page Godot camera controls with coalesced updates,
restart-safe session handling, and stale request protection.
- Kept scene input simple: Electron does not cache the selected model
for replay. Each Godot start receives the current model selection from
the renderer.

## File Guide

Shared contracts:

- `packages/stage-shared/src/godot-stage/view-state.ts` defines the
Godot view-state contract and schema validation.
- `packages/stage-shared/src/godot-stage/index.ts` exports the Godot
shared contract surface.
- `packages/stage-shared/package.json` exposes the new shared entry.

Electron / renderer bridge:

- `apps/stage-tamagotchi/src/shared/eventa/index.ts` adds the Eventa
contracts for Godot status, scene input, view snapshot, patch, and error
events.
- `apps/stage-tamagotchi/src/main/services/airi/godot-stage/index.ts`
owns the Godot sidecar lifecycle, local WebSocket bridge, scene input
forwarding, and view-state forwarding.

Settings page:

- `apps/stage-tamagotchi/src/renderer/pages/settings/models/index.vue`
wires the settings page to Godot status, scene input, snapshots, and
patches.
-
`apps/stage-tamagotchi/src/renderer/pages/settings/models/godot-view-patch-queue.ts`
coalesces high-frequency camera edits before sending them to Godot.
-
`apps/stage-tamagotchi/src/renderer/pages/settings/models/godot-view-session.ts`
tracks renderer-local Godot session epochs so stale async results are
ignored.

Shared settings UI:

-
`packages/stage-ui/src/components/scenarios/settings/model-settings/godot.vue`
renders the Godot camera controls.
-
`packages/stage-ui/src/components/scenarios/settings/model-settings/panel.vue`
routes the model settings panel between Live2D, VRM, and Godot settings.
-
`packages/stage-ui/src/components/scenarios/settings/model-settings/runtime.ts`
resolves model-settings runtime display state and Godot camera control
range.
- `packages/stage-ui/src/components/data-pane/property-number.vue`
updates number control behavior so config changes such as min/max/range
are reflected correctly.

Godot runtime:

- `engines/stage-tamagotchi-godot/scripts/StageRoot.cs` wires scene
loading, view runtime, and transport together.
- `engines/stage-tamagotchi-godot/scripts/scene/StageSceneController.cs`
loads VRM avatars and normalizes avatar facing direction.
- `engines/stage-tamagotchi-godot/scripts/view/StageViewRuntime.cs` owns
Godot view-state updates, snapshots, patch application, and idle
persistence.
-
`engines/stage-tamagotchi-godot/scripts/view/StageCameraPoseController.cs`
computes avatar bounds, bootstraps the camera, applies camera pose, and
handles camera movement math.
-
`engines/stage-tamagotchi-godot/scripts/view/StageCameraInputController.cs`
maps mouse and keyboard input into camera operations.
- `engines/stage-tamagotchi-godot/scripts/view/StageViewStateRules.cs`
centralizes view-state defaults and validation rules.
- `engines/stage-tamagotchi-godot/scripts/view/StageViewStateStore.cs`
persists and loads Godot camera view state.
- `engines/stage-tamagotchi-godot/scripts/transport/StageViewJson.cs`
parses and serializes view-state transport payloads.
-
`engines/stage-tamagotchi-godot/scripts/transport/StageViewPayloads.cs`
defines the C# payload records used by the transport layer.

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>