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/setuptools/_shutil.py

@@ -0,0 +1,53 @@
+"""Convenience layer on top of stdlib's shutil and os"""
+
+import os
+import stat
+from typing import Callable, TypeVar
+
+from .compat import py311
+
+from distutils import log
+
+try:
+    from os import chmod  # pyright: ignore[reportAssignmentType]
+    # Losing type-safety w/ pyright, but that's ok
+except ImportError:  # pragma: no cover
+    # Jython compatibility
+    def chmod(*args: object, **kwargs: object) -> None:  # type: ignore[misc] # Mypy reuses the imported definition anyway
+        pass
+
+
+_T = TypeVar("_T")
+
+
+def attempt_chmod_verbose(path, mode):
+    log.debug("changing mode of %s to %o", path, mode)
+    try:
+        chmod(path, mode)
+    except OSError as e:  # pragma: no cover
+        log.debug("chmod failed: %s", e)
+
+
+# Must match shutil._OnExcCallback
+def _auto_chmod(
+    func: Callable[..., _T], arg: str, exc: BaseException
+) -> _T:  # pragma: no cover
+    """shutils onexc callback to automatically call chmod for certain functions."""
+    # Only retry for scenarios known to have an issue
+    if func in [os.unlink, os.remove] and os.name == 'nt':
+        attempt_chmod_verbose(arg, stat.S_IWRITE)
+        return func(arg)
+    raise exc
+
+
+def rmtree(path, ignore_errors=False, onexc=_auto_chmod):
+    """
+    Similar to ``shutil.rmtree`` but automatically executes ``chmod``
+    for well know Windows failure scenarios.
+    """
+    return py311.shutil_rmtree(path, ignore_errors, onexc)
+
+
+def rmdir(path, **opts):
+    if os.path.isdir(path):
+        rmtree(path, **opts)