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/Scripts/SpectatorSetup.cs.meta

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