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/ProjectSettings/NavMeshAreas.asset

@@ -73,10 +73,10 @@ NavMeshProjectSettings:
   m_Settings:
   - serializedVersion: 2
     agentTypeID: 0
-    agentRadius: 0.5
-    agentHeight: 2
+    agentRadius: 0.3
+    agentHeight: 1.8
     agentSlope: 45
-    agentClimb: 0.75
+    agentClimb: 0.25
     ledgeDropHeight: 0
     maxJumpAcrossDistance: 0
     minRegionArea: 2