Add BetterCam engine, UI polish, and bug fixes

- Add BetterCam capture engine (DXGI Desktop Duplication, priority 4)
- Fix missing picture_stream_id in get_device endpoint
- Fix template delete validation to check streams instead of devices
- Add description field to capture engine template UI
- Default template name changed to "Default" with descriptive text
- Display picker highlights selected display instead of primary
- Fix modals closing when dragging text selection outside dialog
- Rename "Engine Configuration" to "Configuration", hide when empty
- Rename "Run Test" to "Run" across all test buttons
- Always reserve space for vertical scrollbar
- Redesign Stream Settings info panel with pill-style props
- Fix processed stream showing internal ID instead of stream name
- Update en/ru locale files

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

server/src/wled_controller/api/routes.py

@@ -389,6 +389,7 @@ async def get_device(
         ),
         calibration=CalibrationSchema(**calibration_to_dict(device.calibration)),
         capture_template_id=device.capture_template_id,
+        picture_stream_id=device.picture_stream_id,
         created_at=device.created_at,
         updated_at=device.updated_at,
     )
@@ -918,25 +919,25 @@ async def delete_template(
     template_id: str,
     _auth: AuthRequired,
     template_store: TemplateStore = Depends(get_template_store),
-    device_store: DeviceStore = Depends(get_device_store),
+    stream_store: PictureStreamStore = Depends(get_picture_stream_store),
 ):
     """Delete a template.
 
-    Validates that no devices are currently using this template before deletion.
+    Validates that no streams are currently using this template before deletion.
     """
     try:
-        # Check if any devices are using this template
-        devices_using_template = []
-        for device in device_store.get_all_devices():
-            if device.capture_template_id == template_id:
-                devices_using_template.append(device.name)
+        # Check if any streams are using this template
+        streams_using_template = []
+        for stream in stream_store.get_all_streams():
+            if stream.capture_template_id == template_id:
+                streams_using_template.append(stream.name)
 
-        if devices_using_template:
-            device_list = ", ".join(devices_using_template)
+        if streams_using_template:
+            stream_list = ", ".join(streams_using_template)
             raise HTTPException(
                 status_code=409,
-                detail=f"Cannot delete template: it is currently assigned to the following device(s): {device_list}. "
-                       f"Please reassign these devices to a different template before deleting."
+                detail=f"Cannot delete template: it is used by the following stream(s): {stream_list}. "
+                       f"Please reassign these streams to a different template before deleting."
             )
 
         # Proceed with deletion
@@ -1036,6 +1037,10 @@ async def test_template(
             screen_capture = engine.capture_display(test_request.display_index)
             capture_elapsed = time.perf_counter() - capture_start
 
+            # Skip if no new frame (screen unchanged)
+            if screen_capture is None:
+                continue
+
             total_capture_time += capture_elapsed
             frame_count += 1
             last_frame = screen_capture
@@ -1354,6 +1359,9 @@ async def test_pp_template(
                 screen_capture = engine.capture_display(display_index)
                 capture_elapsed = time.perf_counter() - capture_start
 
+                if screen_capture is None:
+                    continue
+
                 total_capture_time += capture_elapsed
                 frame_count += 1
                 last_frame = screen_capture
@@ -1739,6 +1747,9 @@ async def test_picture_stream(
                 screen_capture = engine.capture_display(display_index)
                 capture_elapsed = time.perf_counter() - capture_start
 
+                if screen_capture is None:
+                    continue
+
                 total_capture_time += capture_elapsed
                 frame_count += 1
                 last_frame = screen_capture