Add free-camera mode with player-equivalent collision

Introduce a free-fly camera as the next entry in the Tab mode cycle
(Player Control -> Paint -> Free Cam):

- FreeCamController: dedicated CinemachineCamera plus a CharacterController
  mirroring the player capsule (radius 0.1, height 1.3, slope 59, step 0.15)
  so the free camera collides with walls/ceiling/floor exactly like the
  player. WASD/Q-E (and Space/Ctrl) fly relative to view; mouse looks.
- FreeCamMode: plain-C# GameMode mirroring PaintMode, with an Exit() that
  restores camera priority and re-enables player control + camera input.
- GameModeManager: register freeCam in the Tab cycle (gated like player).
- Scene: FreeCamera object wired, Main Camera custom blends (0.4s) for the
  vcam priority hand-off.

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

Assets/Scripts/GameModeManager.cs

@@ -5,7 +5,7 @@ using UnityEngine.InputSystem;
 #endif
 
 /// <summary>
-/// Switches the game between high-level modes (Player Control, Paint). The switch
+/// Switches the game between high-level modes (Player Control, Paint, Free Cam). The switch
 /// key (Tab) cycles to the next registered mode. Register additional modes in
 /// <see cref="BuildModes"/>. Attach to a single, persistent scene GameObject.
 /// </summary>
@@ -22,6 +22,9 @@ public class GameModeManager : MonoBehaviour
     [Tooltip("Mesh painter. Empty = found automatically.")]
     public MeshPainter painter;
 
+    [Tooltip("Free-fly spectator camera. Empty = found automatically. Absent = Free Cam is left out of the cycle.")]
+    public FreeCamController freeCam;
+
     //[Tooltip("Insect / surface-walk controller. Empty = found automatically.")]
     //public InsectController insect;
 
@@ -39,6 +42,7 @@ public class GameModeManager : MonoBehaviour
     public PlayerCharacterController Player => player;
     public ThirdPersonOrbitInput CameraInput => cameraInput;
     public MeshPainter Painter => painter;
+    public FreeCamController FreeCam => freeCam;
     //public InsectController Insect => insect;
 
     /// <summary>Raised after a mode switch finishes (the new mode's Enter has already run).
@@ -57,6 +61,8 @@ public class GameModeManager : MonoBehaviour
         if (!player) player = FindFirstObjectByType<PlayerCharacterController>();
         if (!cameraInput) cameraInput = FindFirstObjectByType<ThirdPersonOrbitInput>();
         if (!painter) painter = FindFirstObjectByType<MeshPainter>();
+        // Include inactive so a freecam rig that starts disabled is still found and wired.
+        if (!freeCam) freeCam = FindFirstObjectByType<FreeCamController>(FindObjectsInactive.Include);
         //if (!insect) insect = FindFirstObjectByType<InsectController>();
 
         BuildModes();
@@ -80,6 +86,10 @@ public class GameModeManager : MonoBehaviour
 
         _modes.Add(new PaintMode());
 
+        // Free Cam only joins the cycle when a freecam rig is present, so scenes without one are unchanged.
+        if (freeCam)
+            _modes.Add(new FreeCamMode());
+
         // Insect mode only joins the Tab cycle when a surface walker is present, so a scene
         // without one behaves exactly as before (no dead, player-freezing mode in the cycle).
         //if (insect)