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)

addons/netfox/properties/property-entry.gd

@@ -0,0 +1,51 @@
+extends RefCounted
+class_name PropertyEntry
+
+var _path: String
+var node: Node
+var property: String
+
+static var _logger := NetfoxLogger._for_netfox("PropertyEntry")
+
+func get_value() -> Variant:
+	return node.get_indexed(property)
+
+func set_value(value):
+	node.set_indexed(property, value)
+
+func is_valid() -> bool:
+	if not node or not is_instance_valid(node):
+		# Node is invalid
+		return false
+
+	# Return true if node has given property
+	return node.get_property_list()\
+		.any(func(it): return it["name"] == property)
+
+func _to_string() -> String:
+	return _path
+
+static func parse(root: Node, path: String) -> PropertyEntry:
+	var result = PropertyEntry.new()
+	result.node = root.get_node(NodePath(path))
+	result.property = path.erase(0, path.find(":") + 1)
+	result._path = path
+	return result
+
+static func make_path(root: Node, node: Variant, property: String) -> String:
+	var node_path := ""
+
+	if node is String:
+		node_path = node
+	elif node is NodePath:
+		node_path = str(node)
+	elif node is Node:
+		node_path = str(root.get_path_to(node))
+	else:
+		_logger.error("Can't stringify node reference: %s", [node])
+		return ""
+
+	if node_path == ".":
+		node_path = ""
+
+	return "%s:%s" % [node_path, property]