Add per-target protocol selection (DDP/HTTP) and reorganize target editor

- Add protocol field (ddp/http) to storage, API schemas, routes, processor
- WledTargetProcessor passes protocol to create_led_client(use_ddp=...)
- Target editor: protocol dropdown + keepalive in collapsible Specific Settings
- FPS, brightness threshold, adaptive FPS moved to main form area
- Hide Specific Settings section for serial devices (protocol is WLED-only)
- Card badge: show DDP/HTTP for WLED devices, Serial for serial devices

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

server/src/wled_controller/api/routes/picture_targets.py

@@ -102,6 +102,7 @@ def _target_to_response(target) -> PictureTargetResponse:
             state_check_interval=target.state_check_interval,
             min_brightness_threshold=target.min_brightness_threshold,
             adaptive_fps=target.adaptive_fps,
+            protocol=target.protocol,
             description=target.description,
             auto_start=target.auto_start,
             created_at=target.created_at,
@@ -163,6 +164,7 @@ async def create_target(
             state_check_interval=data.state_check_interval,
             min_brightness_threshold=data.min_brightness_threshold,
             adaptive_fps=data.adaptive_fps,
+            protocol=data.protocol,
             picture_source_id=data.picture_source_id,
             key_colors_settings=kc_settings,
             description=data.description,
@@ -282,6 +284,7 @@ async def update_target(
             state_check_interval=data.state_check_interval,
             min_brightness_threshold=data.min_brightness_threshold,
             adaptive_fps=data.adaptive_fps,
+            protocol=data.protocol,
             key_colors_settings=kc_settings,
             description=data.description,
             auto_start=data.auto_start,