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

export_presets.cfg

@@ -1,13 +1,13 @@
 [preset.0]
-name="Linux Server"
-platform="Linux/X11"
+name="Windows Desktop"
+platform="Windows Desktop"
 runnable=true
-dedicated_server=true
+dedicated_server=false
 custom_features=""
 export_filter="all_resources"
 include_filter=""
 exclude_filter=""
-export_path="build/tactical-shooter-server.x86_64"
+export_path="build/tactical-shooter-windows-x86_64/tactical-shooter.exe"
 patches=PackedStringArray()
 encryption_include_filters=""
 encryption_exclude_filters=""
@@ -29,19 +29,55 @@ codesign/identity=""
 codesign/timestamp=true
 codesign/timestamp_server_url=""
 application/icon=""
+application/identifier="tactical-shooter-client"
+application/name="Tactical Shooter"
+application/app_category="game"
+application/file_version="0.1.0"
+application/product_version="0.1.0"
+display/width=1280
+display/height=720
+xr_features/enabled=false
+xr_features/hand_tracking=false
+xr_features/passthrough=false
+
+[preset.1]
+name="Linux Server"
+platform="Linux/X11"
+runnable=true
+dedicated_server=true
+custom_features=""
+export_filter="all_resources"
+include_filter=""
+exclude_filter=""
+export_path="build/tactical-shooter-server.x86_64"
+patches=PackedStringArray()
+encryption_include_filters=""
+encryption_exclude_filters=""
+encrypt_pck=false
+encrypt_directory=false
+script_encryption_key=""
+
+[preset.1.options]
+custom_template/debug=""
+custom_template/release=""
+binary_format/embed_pck=true
+binary_format/architecture="x86_64"
+texture_format/s3tc_bptc=true
+texture_format/etc2_astc=false
+texture_format/no_bptc_fallbacks=true
+dotnet/include_scripts_content=false
+dotnet/rollforward_to_latest_prerelease=true
+codesign/identity=""
+codesign/timestamp=true
+codesign/timestamp_server_url=""
+application/icon=""
 application/identifier="tactical-shooter-server"
 application/name="Tactical Shooter Server"
 application/app_category="game"
 application/file_version="0.1.0"
 application/product_version="0.1.0"
-application/company_name=""
-application/copyright=""
-application/trademarks=""
 display/width=1
 display/height=1
-display/handheld/dpi=72
-display/handheld/dpi_mode="disabled"
-display/scale_mode="disabled"
 xr_features/enabled=false
 xr_features/hand_tracking=false
 xr_features/passthrough=false