Phase 7: netfox + godot-jolt stack upgrade

Stack installed:
- netfox v1.35.3 (core + extras + noray + internals)
- godot-jolt v0.16.0-stable

Architecture:
- Server: ENet transport (works headless, no netfox deps)
- Client/Editor: netfox rollback (RollbackSynchronizer, TickInterpolator)

New/modified:
- docs/migration-netfox-plan.md — migration architecture
- scripts/network/network_manager.gd — netfox-aware ENet fallback
- scripts/network/player.gd — clean base player
- client/characters/player_netfox.gd — rollback player w/ WeaponManager
- client/characters/input/player_net_input.gd — BaseNetInput subclass
- client/characters/character/fps_character_controller.gd — netfox input feed
- client/weapons/ — weapon data, registry, TacticalWeaponHitscan, WeaponManager
- client/scripts/round_replicator.gd — client-side round state bridge
- server/scripts/round_manager.gd — improved state machine
- server/scripts/plugin_api/plugin_manager.gd — refined plugin system
- config: enemy_tag, ally_tag for meatball targeting

Removed: old C++ SimulationServer GDExtension (replaced by netfox rollback)

server/server-browser-api/venv/lib/python3.11/site-packages/websockets/http.py

@@ -0,0 +1,20 @@
+from __future__ import annotations
+
+import warnings
+
+from .datastructures import Headers, MultipleValuesError  # noqa: F401
+
+
+with warnings.catch_warnings():
+    # Suppress redundant DeprecationWarning raised by websockets.legacy.
+    warnings.filterwarnings("ignore", category=DeprecationWarning)
+    from .legacy.http import read_request, read_response  # noqa: F401
+
+
+warnings.warn(  # deprecated in 9.0 - 2021-09-01
+    "Headers and MultipleValuesError were moved "
+    "from websockets.http to websockets.datastructures"
+    "and read_request and read_response were moved "
+    "from websockets.http to websockets.legacy.http",
+    DeprecationWarning,
+)