Add capture template system with in-memory defaults and split device settings UI

- Generate default templates (MSS, DXcam, WGC) in memory from EngineRegistry at startup
- Only persist user-created templates to JSON, skip defaults on load/save
- Add capture_template_id to Device model and DeviceCreate schema
- Remember last used template in localStorage, use it for new devices with fallback
- Split Device Settings dialog into General Settings and Capture Settings
- Add capture settings button (🎬) to device card
- Separate default and custom templates with visual separator in Templates tab
- Add capture engine integration to ProcessorManager
- Add CLAUDE.md with git commit/push policy and server restart instructions
- Add en/ru localization for all new UI elements

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/pyproject.toml

@@ -48,6 +48,11 @@ dev = [
     "black>=24.0.0",
     "ruff>=0.6.0",
 ]
+# High-performance screen capture engines (Windows only)
+perf = [
+    "dxcam>=0.0.5; sys_platform == 'win32'",
+    "windows-capture>=1.5.0; sys_platform == 'win32'",
+]
 
 [project.urls]
 Homepage = "https://git.dolgolyov-family.by/alexei.dolgolyov/wled-screen-controller-mixed"