Implement zone dimension display and zone repositioning in editor

Feature #15 - Show Zone Dimensions:
- Display real-time dimensions while drawing zones
- Show width x height in both pixels and percentages
- Display position coordinates (x, y)
- Dimension label follows cursor with 15px offset
- Label positioned to stay within monitor bounds
- Automatically cleaned up when zone drawing completes

Feature #16 - Move/Reposition Zones:
- Click on existing zones to select and move them
- Yellow highlight when zone is being moved (vs green for new zones)
- Drag zones to new positions while maintaining size
- Constrain movement to monitor bounds (can't move outside screen)
- Real-time update of zone coordinates in data structure
- Green color restored after move completes

Editor Improvements:
- Added zoneActors array to track zone widgets for moving
- Updated instruction label to mention zone moving
- Enhanced _findZoneAtPosition() helper to detect clicks on zones
- Improved _removeLastZone() to properly clean up zone actors
- Better cleanup in _cancelEditor() to prevent memory leaks
- Track moving state (isMovingZone, movingZoneIndex, moveOffsetX/Y)

UX Enhancements:
- Separate visual feedback for creating (green) vs moving (yellow) zones
- Smooth drag experience with proper offset tracking
- Dimensions update in real-time during zone creation
- Clear visual distinction between zone operations

Fixes TODO items #15 and #16

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

TODO.md

@@ -43,22 +43,22 @@
 - [ ] Add UI to choose which layout to edit
 - [ ] Pre-populate editor with existing zones when editing
 
-### 15. Show Zone Dimensions in Editor
+### 15. Show Zone Dimensions in Editor ✅ COMPLETED
 **Priority: Medium**
-- [ ] Display zone dimensions while drawing in graphical editor
-- [ ] Show width and height in pixels and/or percentage
-- [ ] Update dimensions in real-time as zone is resized
-- [ ] Display position coordinates (x, y)
-- [ ] Show dimensions near cursor or inside zone preview
+- [x] Display zone dimensions while drawing in graphical editor
+- [x] Show width and height in pixels and/or percentage
+- [x] Update dimensions in real-time as zone is resized
+- [x] Display position coordinates (x, y)
+- [x] Show dimensions near cursor or inside zone preview
 
-### 16. Move/Reposition Zones in Editor
+### 16. Move/Reposition Zones in Editor ✅ COMPLETED
 **Priority: Medium**
-- [ ] Allow clicking and dragging existing zones to move them
-- [ ] Visual feedback when zone is selected for moving
-- [ ] Snap to grid or guides (optional)
-- [ ] Prevent moving zones outside monitor bounds
-- [ ] Update zone coordinates as zone is moved
-- [ ] Maintain zone size while moving (only change position)
+- [x] Allow clicking and dragging existing zones to move them
+- [x] Visual feedback when zone is selected for moving (yellow highlight)
+- [x] Prevent moving zones outside monitor bounds
+- [x] Update zone coordinates as zone is moved
+- [x] Maintain zone size while moving (only change position)
+- [ ] Snap to grid or guides (future enhancement)
 
 ## Code Quality & Robustness