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/handle.pxd

@@ -0,0 +1,48 @@
+cdef class UVHandle:
+    cdef:
+        uv.uv_handle_t *_handle
+        Loop _loop
+        readonly _source_traceback
+        bint _closed
+        bint _inited
+        object context
+
+        # Added to enable current UDPTransport implementation,
+        # which doesn't use libuv handles.
+        bint _has_handle
+
+    # All "inline" methods are final
+
+    cdef inline _start_init(self, Loop loop)
+    cdef inline _abort_init(self)
+    cdef inline _finish_init(self)
+
+    cdef inline bint _is_alive(self)
+    cdef inline _ensure_alive(self)
+
+    cdef _error(self, exc, throw)
+    cdef _fatal_error(self, exc, throw, reason=?)
+
+    cdef _warn_unclosed(self)
+
+    cdef _free(self)
+    cdef _close(self)
+
+
+cdef class UVSocketHandle(UVHandle):
+    cdef:
+        # Points to a Python file-object that should be closed
+        # when the transport is closing.  Used by pipes.  This
+        # should probably be refactored somehow.
+        object _fileobj
+        object __cached_socket
+
+    # All "inline" methods are final
+
+    cdef _fileno(self)
+
+    cdef _new_socket(self)
+    cdef inline _get_socket(self)
+    cdef inline _attach_fileobj(self, object file)
+
+    cdef _open(self, int sockfd)