refactor: key colors targets → CSS source type, HA target improvements

Key Colors refactor:
- New `key_colors` CSS source type with inline rectangles
- KeyColorsColorStripStream: extracts N colors from screen regions
- CSS editor: EntitySelect for picture source, IconSelect for color mode
- Configure Regions button on card opens pattern canvas editor
- Live WS preview at 5 FPS with rectangle overlay + color swatches
- Removed KC target type, pattern template entity, and related API routes
- Removed KC/pattern template sections from Targets tab

HA light target improvements:
- Update rate, transition, mappings, brightness VS now editable via PUT
- Card crosslinks for HA source, CSS source, brightness VS
- HA connection status icon, text metrics (Hz, uptime)
- Brightness value source selector in editor

server/src/wled_controller/static/css/automations.css

@@ -83,8 +83,18 @@
     border: none;
     color: var(--danger-color, #dc3545);
     cursor: pointer;
-    font-size: 1rem;
     padding: 2px 6px;
+    opacity: 0.7;
+    transition: opacity 0.15s;
+}
+
+.btn-remove-condition:hover {
+    opacity: 1;
+}
+
+.btn-remove-condition .icon {
+    width: 16px;
+    height: 16px;
 }
 
 .condition-fields {