✨ Update progress on GamemasterExplorer refactoring with new composable extraction and additional tests

docs/projects/Pokedex.Online/PROGRESS.md

@@ -121,7 +121,7 @@ Last Updated: January 28, 2026
 
 ---
 
-## Phase 5: GamemasterExplorer Refactoring (1/9 complete)
+## Phase 5: GamemasterExplorer Refactoring (2/9 complete)
 **Duration**: 5-7 days  
 **Status**: In Progress  
 **Target**: Reduce from 1627 lines → ~400 lines (76% reduction)
@@ -132,12 +132,19 @@ Last Updated: January 28, 2026
 - [x] Extract search methods (executeSearch, clearSearch, goToNextResult, goToPrevResult)
 - [x] Support regex patterns and fallback synchronous search
 - [x] Write comprehensive tests - 35 tests passing ✅
-  - Initialization and state management
-  - Search navigation (next/prev with wrapping)
-  - Text highlighting with regex escaping
-  - Computed properties (currentResultLineNumber, resultCountDisplay, hasSearchResults)
-  - Error handling and cleanup
-  - History integration
+
+### ✅ Step 14: Extract useGamemasterFiles Composable
+- [x] Create `src/composables/useGamemasterFiles.js` - Full file loading & management
+- [x] Extract file state (selectedFile, fileContent, fileLines, displayLines)
+- [x] Extract file methods (loadStatus, loadFile, clearFileSelection, updateDisplayLines)
+- [x] Support pagination and virtual scrolling preparation
+- [x] Write comprehensive tests - 45 tests passing ✅
+  - File loading for all types (pokemon, moves, allForms, raw)
+  - File size validation (50MB limit for raw files)
+  - Display line pagination (10K lines initially)
+  - Preference persistence
+  - JSON path extraction for filtering
+  - Error handling and state management
 
 ### ⏳ Step 14: Extract useGamemasterFiles Composable
 - [ ] Create `src/composables/useGamemasterFiles.js`