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/websockets/sync/utils.py

@@ -0,0 +1,45 @@
+from __future__ import annotations
+
+import time
+
+
+__all__ = ["Deadline"]
+
+
+class Deadline:
+    """
+    Manage timeouts across multiple steps.
+
+    Args:
+        timeout: Time available in seconds or :obj:`None` if there is no limit.
+
+    """
+
+    def __init__(self, timeout: float | None) -> None:
+        self.deadline: float | None
+        if timeout is None:
+            self.deadline = None
+        else:
+            self.deadline = time.monotonic() + timeout
+
+    def timeout(self, *, raise_if_elapsed: bool = True) -> float | None:
+        """
+        Calculate a timeout from a deadline.
+
+        Args:
+            raise_if_elapsed: Whether to raise :exc:`TimeoutError`
+                if the deadline lapsed.
+
+        Raises:
+            TimeoutError: If the deadline lapsed.
+
+        Returns:
+            Time left in seconds or :obj:`None` if there is no limit.
+
+        """
+        if self.deadline is None:
+            return None
+        timeout = self.deadline - time.monotonic()
+        if raise_if_elapsed and timeout <= 0:
+            raise TimeoutError("timed out")
+        return timeout