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

client/scripts/bake_lighting.gd.uid

@@ -0,0 +1 @@
+uid://q8nutj781fyf

client/scripts/bake_lightmaps.gd.uid

@@ -0,0 +1 @@
+uid://d0mbp6gs2mwlr

client/scripts/test_headless.gd.uid

@@ -0,0 +1 @@
+uid://dbtpbhja3nk60

client/scripts/validate_lights.gd.uid

@@ -0,0 +1 @@
+uid://cwvi2ic1k6ubn

client/scripts/validate_map.gd.uid

@@ -0,0 +1 @@
+uid://olpdh1gx2gca

client/scripts/validate_polycount.gd.uid

@@ -0,0 +1 @@
+uid://bqau1kivb87fk

client/scripts/validate_scene.gd.uid

@@ -0,0 +1 @@
+uid://d0go24t1lsx2j

client/scripts/validate_textures.gd.uid

@@ -0,0 +1 @@
+uid://bas55o1773n21