Fix headless class_name dependencies

- Replaced TeamData.Team type hints with int in all scripts
- Added explicit preloads for headless mode class resolution
- Created stub LagCompensation and DamageProcessor scripts
- Fixed PluginManager, SpawnManager, EconomyManager, BuyZone,
  RoundManager, BuyMenuHandler, BombObjective class_name references
- Updated server config to match ServerConfig.gd format

Gray screen root cause: server scripts failed to parse in headless
mode due to Godot 4 class_name loading order (Resource after Node),
leaving server_main.gd non-functional — accepted connections but
never spawned players.

server/scripts/plugin_api/plugin_manager.gd

@@ -24,6 +24,10 @@ extends Node
 ## Duplicate class_name removed — already registered as autoload singleton.
 ## class_name PluginManager
 
+# Force dependency scripts to load (headless compat)
+const _pm_manifest_ref = preload("res://server/scripts/plugin_api/plugin_manifest.gd")
+const _pm_base_ref = preload("res://server/scripts/plugin_api/plugin_base.gd")
+
 # ---------------------------------------------------------------------------
 # Signals
 # ---------------------------------------------------------------------------
@@ -140,7 +144,7 @@ func rescan() -> int:
 	# Auto-load newly discovered enabled plugins that aren't already loaded.
 	for pname in discovered_manifests:
 		if pname not in loaded_plugins:
-			var manifest: PluginManifest = discovered_manifests[pname]
+			var manifest = discovered_manifests[pname]
 			if manifest.enabled:
 				_load_plugin_from_manifest(pname, manifest)
 
@@ -158,7 +162,7 @@ func _process_plugin_directory(root: String, dir_name: String) -> void:
 		return
 
 	var manifest: Resource = ResourceLoader.load(tres_path)
-	if not manifest is PluginManifest:
+	if manifest == null or manifest.get_script() == null or not manifest.has_method(&"is_valid"):
 		log_warn("Invalid manifest (not a PluginManifest resource): %s" % tres_path)
 		return
 
@@ -197,12 +201,12 @@ func load_plugin(name: String) -> bool:
 		log_err("Plugin not found: %s. Use 'plugin rescan' to scan for new plugins." % name)
 		return false
 
-	var manifest: PluginManifest = discovered_manifests[name]
+	var manifest = discovered_manifests[name]
 	return _load_plugin_from_manifest(name, manifest)
 
 ## Internal: instantiate a plugin from its manifest and add it to the tree.
 ## Handles resource loading, instance creation, and metadata injection.
-func _load_plugin_from_manifest(name: String, manifest: PluginManifest) -> bool:
+func _load_plugin_from_manifest(name: String, manifest) -> bool:
 	var info: Dictionary = _plugin_info.get(name, {})
 	var plugin_dir: String = info.get("path", plugins_root + "/" + name + "/")
 	var script_path: String = plugin_dir + manifest.script_path
@@ -236,7 +240,7 @@ func _load_plugin_from_manifest(name: String, manifest: PluginManifest) -> bool:
 
 	# Warn if the plugin doesn't extend PluginBase (it'll still work,
 	# just won't have convenience methods).
-	if not instance is PluginBase:
+	if instance == null or not instance.has_method(&"log_info"):
 		log_warn("Plugin '%s' does not extend PluginBase — some features may be unavailable" % name)
 
 	# Inject manifest metadata into the instance
@@ -300,7 +304,7 @@ func reload_plugin(name: String) -> bool:
 	unload_plugin(name)
 
 	# Re-acquire manifest info
-	var manifest: PluginManifest = discovered_manifests.get(name)
+	var manifest = discovered_manifests.get(name)
 	if not manifest:
 		log_err("Manifest lost for plugin '%s' during reload" % name)
 		return false
@@ -496,7 +500,7 @@ func _rcon_list(_args: PackedStringArray) -> String:
 		lines.append("  No plugins discovered. Use 'plugin rescan' to scan.")
 	else:
 		for pname in all_names:
-			var manifest: PluginManifest = discovered_manifests[pname]
+			var manifest = discovered_manifests[pname]
 			var status: String
 			if pname in loaded_plugins:
 				status = "LOADED"
@@ -543,7 +547,7 @@ func _rcon_info(args: PackedStringArray) -> String:
 	if name not in discovered_manifests:
 		return "Plugin not found: %s. Use 'plugin list' to see available plugins.\\r\\n" % name
 
-	var manifest: PluginManifest = discovered_manifests[name]
+	var manifest = discovered_manifests[name]
 	var info: Dictionary = _plugin_info.get(name, {})
 	var full_script_path: String = info.get("path", "") + manifest.script_path
 	var lines: PackedStringArray = []