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/poll.pxd

@@ -0,0 +1,25 @@
+cdef class UVPoll(UVHandle):
+    cdef:
+        int fd
+        Handle reading_handle
+        Handle writing_handle
+
+    cdef _init(self, Loop loop, int fd)
+    cdef _close(self)
+
+    cdef inline _poll_start(self, int flags)
+    cdef inline _poll_stop(self)
+
+    cdef int is_active(self) noexcept
+
+    cdef is_reading(self)
+    cdef is_writing(self)
+
+    cdef start_reading(self, Handle callback)
+    cdef start_writing(self, Handle callback)
+    cdef stop_reading(self)
+    cdef stop_writing(self)
+    cdef stop(self)
+
+    @staticmethod
+    cdef UVPoll new(Loop loop, int fd)