docs: update refactoring progress - Phase 2 complete

Update progress document to reflect Phase 2 completion:
- Add useRegionDetection hook details (~100 lines encapsulated)
- Mark Phase 2 as complete
- Update file list with new hook
- Update commit history
- Update next steps for Phase 3

Phase 2 achievements:
- ✅ usePointerLock (119 lines)
- ✅ useMagnifierZoom (240 lines)
- ✅ useRegionDetection (238 lines)

Ready to begin Phase 3: Integrate hooks into MapRenderer.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/arcade-games/know-your-world/.refactoring-progress.md

@@ -45,8 +45,16 @@ The MapRenderer.tsx component had grown to 2409 lines with significant code dupl
    - Recalculation of capped zoom on pointer lock release
    - **Impact**: Replaces ~150 lines of zoom-related logic in MapRenderer
 
-**Still TODO:**
-- `hooks/useRegionDetection.ts` - Region detection for zoom calculation
+3. **`hooks/useRegionDetection.ts`** ✅
+   - Detection box around cursor (configurable size)
+   - Region overlap detection with bounding box checks
+   - Region-under-cursor detection (closest to center)
+   - Size tracking for adaptive behaviors
+   - Small region detection (< 15px or < 200px² area)
+   - Returns sorted DetectedRegion[] (smallest first)
+   - **Impact**: Encapsulates ~100 lines of region detection logic
+
+**Phase 2 Complete!** All planned hooks have been extracted.
 
 ## Remaining Work
 
@@ -54,9 +62,8 @@ The MapRenderer.tsx component had grown to 2409 lines with significant code dupl
 - Extract adaptive zoom search algorithm to `utils/adaptiveZoomSearch.ts`
   - **Note**: This is complex (~200 lines) and can be done separately
 
-### Phase 2 (Partial)
-- Create `useRegionDetection` hook
-- Create `useMagnifierPosition` hook (optional)
+### Phase 2 ✅ Complete
+No remaining work - all planned hooks extracted.
 
 ### Phase 3
 - Simplify MapRenderer to compose hooks
@@ -88,6 +95,7 @@ The MapRenderer.tsx component had grown to 2409 lines with significant code dupl
 - `utils/zoomCapping.ts` (122 lines)
 - `hooks/usePointerLock.ts` (119 lines)
 - `hooks/useMagnifierZoom.ts` (240 lines)
+- `hooks/useRegionDetection.ts` (238 lines)
 
 ### Modified Files
 - `components/MapRenderer.tsx` (replaced 8 calculations with utility calls)
@@ -95,11 +103,10 @@ The MapRenderer.tsx component had grown to 2409 lines with significant code dupl
 ## Next Steps
 
 When continuing:
-1. Test current changes on dev server
-2. Create remaining hooks (useRegionDetection)
-3. Begin Phase 3 - integrate hooks into MapRenderer
-4. Measure final line count reduction
-5. Create architecture documentation
+1. Test current changes on dev server (hooks not yet integrated)
+2. Begin Phase 3 - integrate hooks into MapRenderer
+3. Measure final line count reduction
+4. Create architecture documentation (Phase 4)
 
 ## Commit History
 
@@ -108,3 +115,4 @@ When continuing:
 3. `44d99bc4` - Phase 1: Extract zoomCapping.ts utility
 4. `d5b16d5f` - Phase 2: Extract usePointerLock hook
 5. `ef86f00f` - Phase 2: Extract useMagnifierZoom hook
+6. `dce07591` - Phase 2: Extract useRegionDetection hook