add camera rig, click-to-move locomotion, and click interaction

Camera: Cinemachine-based rig with an anchor, a state director, point-of-
interest framing, pan input, and dialogue framing volumes.

Player: click-to-move over the NavMesh, a pointer input layer, and a motion
arbiter that reconciles direct stick input with navigation-driven movement.
The pure math is isolated in NightclubArcadia.Locomotion.Math with an EditMode
suite, so the arbitration rules are testable without a scene.

Interaction: IClickInteractable plus a bridge that routes pointer clicks to it.

Supporting project settings: adds the Cinemachine package, the Interactable and
Ground tags the raycasts depend on, and NavMesh agent dimensions matched to the
player capsule (radius 0.3, height 1.8, climb 0.25).

Co-Authored-By: Claude Opus 5 <[email protected]>

NightclubArcadia/Packages/manifest.json

@@ -1,6 +1,7 @@
 {
   "dependencies": {
     "com.unity.ai.navigation": "2.0.14",
+    "com.unity.cinemachine": "3.1.7",
     "com.unity.collab-proxy": "2.13.5",
     "com.unity.ide.rider": "3.0.38",
     "com.unity.ide.visualstudio": "2.0.26",