perf: reduce portable build size ~40MB — replace winsdk/wmi, migrate cv2 to Pillow

- Replace winsdk (~35MB) with winrt packages (~2.5MB) for OS notification
  listener. API is identical, 93% size reduction.
- Replace wmi (~3-5MB) with ctypes for monitor names (EnumDisplayDevicesW)
  and camera names (SetupAPI). Zero external dependency.
- Migrate cv2.resize/imencode/LUT to Pillow/numpy in 5 files (filters,
  preview helpers, kc_target_processor). OpenCV only needed for camera
  and video stream now.
- Fix DefWindowProcW ctypes overflow on 64-bit Python (pre-existing bug
  in platform_detector display power listener).
- Fix openLightbox import in streams-capture-templates.ts (was using
  broken window cast instead of direct import).
- Add mandatory data migration policy to CLAUDE.md after silent data
  loss incident from storage file rename without migration.

server/pyproject.toml

@@ -37,7 +37,6 @@ dependencies = [
     "python-dateutil>=2.9.0",
     "python-multipart>=0.0.12",
     "jinja2>=3.1.0",
-    "wmi>=1.5.1; sys_platform == 'win32'",
     "zeroconf>=0.131.0",
     "pyserial>=3.5",
     "psutil>=5.9.0",
@@ -61,9 +60,13 @@ dev = [
 camera = [
     "opencv-python-headless>=4.8.0",
 ]
-# OS notification capture
+# OS notification capture (winrt packages are ~2.5MB total vs winsdk's ~35MB)
 notifications = [
-    "winsdk>=1.0.0b10; sys_platform == 'win32'",
+    "winrt-Windows.UI.Notifications>=3.0.0; sys_platform == 'win32'",
+    "winrt-Windows.UI.Notifications.Management>=3.0.0; sys_platform == 'win32'",
+    "winrt-Windows.Foundation>=3.0.0; sys_platform == 'win32'",
+    "winrt-Windows.Foundation.Collections>=3.0.0; sys_platform == 'win32'",
+    "winrt-Windows.ApplicationModel>=3.0.0; sys_platform == 'win32'",
     "dbus-next>=0.2.3; sys_platform == 'linux'",
 ]
 # High-performance screen capture engines (Windows only)