Replace stripped-player spectator with a minimal dedicated prefab

Mid-match joiners now spawn a dedicated empty Spectator prefab (NetworkObject
+ SpectatorSetup only) instead of a fully stripped Player prefab. The FreeCam
rig is a standalone scene object in Main, so the spectator needs no avatar body,
renderer, collider, or CharacterController -- eliminating the leftover-body
artifact and the fragile per-peer strip path entirely.

- SpectatorSetup.cs (new): owner binds GameModeManager.BindSpectator (FreeCam-only)
- Spectator.prefab (new): empty avatar (Transform + NetworkObject + SpectatorSetup),
  registered in DefaultNetworkPrefabs, wired on MatchManager in Main
- GameModeManager: add BindSpectator/BuildSpectatorModes; drop the spectator
  branch from BindLocalPlayer; ReleaseToNoPlayer frees the cursor on teardown
- MatchManager: independent entropy-seeded RNG for fair hunter pick (was sharing
  the global engine RNG and always landing on the same client); spawn the
  spectator prefab for mid-match joiners; cursor-safe return-to-Main teardown
- FreeCamController: guard IgnorePlayerCollision against a disabled capsule

Also bundled (unrelated user asset/UI edits): PaintHudPanel layout tuning,
font atlas (arialroundedmtprocyr_bold SDF), forestpack_foliage material.

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

Assets/Prefabs/PaintHudPanel.prefab

@@ -3527,7 +3527,7 @@ RectTransform:
   m_AnchorMin: {x: 0, y: 1}
   m_AnchorMax: {x: 1, y: 1}
   m_AnchoredPosition: {x: 0, y: 0}
-  m_SizeDelta: {x: 100, y: 0}
+  m_SizeDelta: {x: 0, y: 0}
   m_Pivot: {x: 0.5, y: 1}
 --- !u!114 &6115439559885354559
 MonoBehaviour:
@@ -3542,10 +3542,10 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: UnityEngine.UI::UnityEngine.UI.VerticalLayoutGroup
   m_Padding:
-    m_Left: 4
-    m_Right: 4
-    m_Top: 4
-    m_Bottom: 4
+    m_Left: 6
+    m_Right: 6
+    m_Top: 6
+    m_Bottom: 6
   m_ChildAlignment: 0
   m_Spacing: 3
   m_ChildForceExpandWidth: 1