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/dotenv/ipython.py

@@ -0,0 +1,50 @@
+from IPython.core.magic import Magics, line_magic, magics_class  # type: ignore
+from IPython.core.magic_arguments import (
+    argument,
+    magic_arguments,
+    parse_argstring,
+)  # type: ignore
+
+from .main import find_dotenv, load_dotenv
+
+
+@magics_class
+class IPythonDotEnv(Magics):
+    @magic_arguments()
+    @argument(
+        "-o",
+        "--override",
+        action="store_true",
+        help="Indicate to override existing variables",
+    )
+    @argument(
+        "-v",
+        "--verbose",
+        action="store_true",
+        help="Indicate function calls to be verbose",
+    )
+    @argument(
+        "dotenv_path",
+        nargs="?",
+        type=str,
+        default=".env",
+        help="Search in increasingly higher folders for the `dotenv_path`",
+    )
+    @line_magic
+    def dotenv(self, line):
+        args = parse_argstring(self.dotenv, line)
+        # Locate the .env file
+        dotenv_path = args.dotenv_path
+        try:
+            dotenv_path = find_dotenv(dotenv_path, True, True)
+        except IOError:
+            print("cannot find .env file")
+            return
+
+        # Load the .env file
+        load_dotenv(dotenv_path, verbose=args.verbose, override=args.override)
+
+
+def load_ipython_extension(ipython):
+    """Register the %dotenv magic."""
+    ipython.register_magics(IPythonDotEnv)