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)

client/tools/validate_map/validator_bootstrap.gd

@@ -0,0 +1,31 @@
+@tool
+extends Node
+
+# Bootstrap: loads and runs validate_map.gd from the main scene.
+# Usage:
+#   1. Set project.godot run/main_scene to this scene
+#   2. godot --path client [-- <scene_path>]
+#   3. Then restore the original main_scene
+
+func _ready() -> void:
+	var args := OS.get_cmdline_user_args()
+
+	if args.is_empty():
+		print("Usage: godot --path client [-- <scene_path>]")
+		print("")
+		print("If no scene_path given, validates the default scene.")
+		get_tree().quit(1)
+		return
+
+	var scene_path := args[0]
+
+	# Load and run the validate_map.gd script
+	var validator_script := load("res://tools/validate_map.gd")
+	if validator_script == null:
+		push_error("Failed to load validator script")
+		get_tree().quit(1)
+		return
+
+	var validator := Node.new()
+	validator.set_script(validator_script)
+	add_child(validator)