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/tests/namespaces.py

@@ -0,0 +1,90 @@
+import ast
+import json
+import textwrap
+from pathlib import Path
+
+
+def iter_namespace_pkgs(namespace):
+    parts = namespace.split(".")
+    for i in range(len(parts)):
+        yield ".".join(parts[: i + 1])
+
+
+def build_namespace_package(tmpdir, name, version="1.0", impl="pkg_resources"):
+    src_dir = tmpdir / name
+    src_dir.mkdir()
+    setup_py = src_dir / 'setup.py'
+    namespace, _, rest = name.rpartition('.')
+    namespaces = list(iter_namespace_pkgs(namespace))
+    setup_args = {
+        "name": name,
+        "version": version,
+        "packages": namespaces,
+    }
+
+    if impl == "pkg_resources":
+        tmpl = '__import__("pkg_resources").declare_namespace(__name__)'
+        setup_args["namespace_packages"] = namespaces
+    elif impl == "pkgutil":
+        tmpl = '__path__ = __import__("pkgutil").extend_path(__path__, __name__)'
+    else:
+        raise ValueError(f"Cannot recognise {impl=} when creating namespaces")
+
+    args = json.dumps(setup_args, indent=4)
+    assert ast.literal_eval(args)  # ensure it is valid Python
+
+    script = textwrap.dedent(
+        """\
+        import setuptools
+        args = {args}
+        setuptools.setup(**args)
+        """
+    ).format(args=args)
+    setup_py.write_text(script, encoding='utf-8')
+
+    ns_pkg_dir = Path(src_dir, namespace.replace(".", "/"))
+    ns_pkg_dir.mkdir(parents=True)
+
+    for ns in namespaces:
+        pkg_init = src_dir / ns.replace(".", "/") / '__init__.py'
+        pkg_init.write_text(tmpl, encoding='utf-8')
+
+    pkg_mod = ns_pkg_dir / (rest + '.py')
+    some_functionality = 'name = {rest!r}'.format(**locals())
+    pkg_mod.write_text(some_functionality, encoding='utf-8')
+    return src_dir
+
+
+def build_pep420_namespace_package(tmpdir, name):
+    src_dir = tmpdir / name
+    src_dir.mkdir()
+    pyproject = src_dir / "pyproject.toml"
+    namespace, _, rest = name.rpartition(".")
+    script = f"""\
+        [build-system]
+        requires = ["setuptools"]
+        build-backend = "setuptools.build_meta"
+
+        [project]
+        name = "{name}"
+        version = "3.14159"
+        """
+    pyproject.write_text(textwrap.dedent(script), encoding='utf-8')
+    ns_pkg_dir = Path(src_dir, namespace.replace(".", "/"))
+    ns_pkg_dir.mkdir(parents=True)
+    pkg_mod = ns_pkg_dir / (rest + ".py")
+    some_functionality = f"name = {rest!r}"
+    pkg_mod.write_text(some_functionality, encoding='utf-8')
+    return src_dir
+
+
+def make_site_dir(target):
+    """
+    Add a sitecustomize.py module in target to cause
+    target to be added to site dirs such that .pth files
+    are processed there.
+    """
+    sc = target / 'sitecustomize.py'
+    target_str = str(target)
+    tmpl = '__import__("site").addsitedir({target_str!r})'
+    sc.write_text(tmpl.format(**locals()), encoding='utf-8')