Phase 7: Windows client export, preset fix, code fixes

- Fix: export_presets.cfg — platform='Windows Desktop' (not 'Windows'), Windows as [preset.0]
- Fix: plugin_manager.gd — removed class_name (autoload conflict), fixed multiline % formatting
- Fix: Disabled GDExtension temporarily for clean export
- Add: Windows PE32+ x86_64 client binary (109MB) at build/tactical-shooter-windows-x86_64/
- Add: tactical-shooter-windows.zip (portable zip package)
- Build: Linux server binary (78MB) rebuilt

server/scripts/plugin_api/plugin_base.gd.uid

@@ -0,0 +1 @@
+uid://b7p2vpaanma77

server/scripts/plugin_api/plugin_manager.gd

@@ -21,7 +21,8 @@
 ##   plugin rescan        — re-scan the plugins directory
 
 extends Node
-class_name PluginManager
+## Duplicate class_name removed — already registered as autoload singleton.
+## class_name PluginManager
 
 # ---------------------------------------------------------------------------
 # Signals
@@ -558,8 +559,7 @@ func _rcon_info(args: PackedStringArray) -> String:
 
 func _rcon_rescan(_args: PackedStringArray) -> String:
 	var count: int = rescan()
-	return "Rescan complete: %d manifest(s) found, %d plugin(s) loaded.\\r\\n" %
-		[count, loaded_plugins.size()]
+	return "Rescan complete: %d manifest(s) found, %d plugin(s) loaded.\\r\\n" % [count, loaded_plugins.size()]
 
 # ---------------------------------------------------------------------------
 # Utility / logging

server/scripts/plugin_api/plugin_manager.gd.uid

@@ -0,0 +1 @@
+uid://bjfhqc378oifb

server/scripts/plugin_api/plugin_manifest.gd.uid

@@ -0,0 +1 @@
+uid://de5u8rubtedqh