Remove all migration logic, scroll tutorial targets into view, mock URL uses device ID

- Remove legacy migration code: profiles→automations key fallbacks, segments array
  fallback, standby_interval compat, profile_id compat, wled→led type mapping,
  legacy calibration field, audio CSS migration, default template migration,
  loadTargets alias, wled sub-tab mapping
- Scroll tutorial step targets into view when off-screen
- Mock device URL changed from mock://{led_count} to mock://{device_id},
  hide mock URL badge on device cards

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

server/src/wled_controller/storage/wled_picture_target.py

@@ -105,26 +105,16 @@ class WledPictureTarget(PictureTarget):
 
     @classmethod
     def from_dict(cls, data: dict) -> "WledPictureTarget":
-        """Create from dictionary with backward compatibility."""
-        # New format: direct color_strip_source_id
-        if "color_strip_source_id" in data:
-            css_id = data["color_strip_source_id"]
-        # Old format: segments array — take first segment's css_id
-        elif "segments" in data:
-            segs = data["segments"]
-            css_id = segs[0].get("color_strip_source_id", "") if segs else ""
-        else:
-            css_id = ""
-
+        """Create from dictionary."""
         return cls(
             id=data["id"],
             name=data["name"],
             target_type="led",
             device_id=data.get("device_id", ""),
-            color_strip_source_id=css_id,
+            color_strip_source_id=data.get("color_strip_source_id", ""),
             brightness_value_source_id=data.get("brightness_value_source_id", ""),
             fps=data.get("fps", 30),
-            keepalive_interval=data.get("keepalive_interval", data.get("standby_interval", 1.0)),
+            keepalive_interval=data.get("keepalive_interval", 1.0),
             state_check_interval=data.get("state_check_interval", DEFAULT_STATE_CHECK_INTERVAL),
             min_brightness_threshold=data.get("min_brightness_threshold", 0),
             adaptive_fps=data.get("adaptive_fps", False),