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/uvloop/handles/timer.pxd

@@ -0,0 +1,18 @@
+cdef class UVTimer(UVHandle):
+    cdef:
+        method_t callback
+        object ctx
+        bint running
+        uint64_t timeout
+        uint64_t start_t
+
+    cdef _init(self, Loop loop, method_t callback, object ctx,
+               uint64_t timeout)
+
+    cdef stop(self)
+    cdef start(self)
+    cdef get_when(self)
+
+    @staticmethod
+    cdef UVTimer new(Loop loop, method_t callback, object ctx,
+                     uint64_t timeout)