feat: implement comprehensive JavaScript functionality recovery using TDD

This commit implements 5 major JavaScript features that were lost during
refactoring, using systematic Test-Driven Development methodology:

**Core Features Implemented:**
- Advanced EditState enum with pending changes preservation
- Keyboard shortcuts (Ctrl+Enter accept, Escape cancel)
- Section splitting with dynamic heading detection
- Real-time status tracking with 2-second periodic updates
- Intelligent filename generation with 4-method fallback system

**Technical Improvements:**
- Comprehensive TDD test suites for all functionality
- Professional status panel with color-coded indicators
- Smart filename generation (options→title→URL→heading→timestamp)
- Event-driven architecture with custom event emission
- State preservation during editing transitions

**Files Added:**
- markitect/static/editor.js - Complete JavaScript functionality
- test_*.js - Comprehensive TDD test suites
- LOST_FUNCTIONALITY_ANALYSIS.md - Detailed feature comparison
- TEST_ENVIRONMENT.md - TDD setup documentation

**Updated Documentation:**
- TODO.md - Status tracking and progress documentation

All features are fully tested and integrated into the existing codebase.
The TDD approach proved highly effective for systematic functionality recovery.

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

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

TODO.md

@@ -12,14 +12,40 @@ The structure organizes **future tasks** by their impact, just as a changelog or
 
 This section is for tasks currently being discussed with or worked on by the coding assistant. These are the ephemeral, flow-of-thought tasks.
 
+**📊 STATUS UPDATE (2025-11-02)**: Systematic JavaScript functionality recovery using TDD methodology has made excellent progress. **5 major features** have been successfully implemented and tested:
+
+1. **Advanced EditState Management** ✅ - Implemented enum-based state tracking with pending changes preservation
+2. **Keyboard Shortcuts** ✅ - Added Ctrl+Enter (accept) and Escape (cancel) functionality
+3. **Section Splitting** ✅ - Restored dynamic heading detection with automatic section reorganization
+4. **Real-time Status Tracking** ✅ - Implemented periodic updates with visual status panel (2-second intervals)
+5. **Intelligent Filename Generation** ✅ - Added 4-method fallback system (options→title→URL→heading→timestamp)
+
+All implementations include comprehensive TDD test suites and are fully integrated into the existing codebase. The recovery approach has proven highly effective for restoring sophisticated lost functionality.
+
 * **To Add:**
-    * None currently identified
+    * ✅ Advanced state management with EditState enum and pending changes (CRITICAL) - COMPLETED
+    * ✅ Keyboard shortcuts (Ctrl+Enter accept, Escape cancel) (CRITICAL) - COMPLETED
+    * ✅ Section splitting functionality for dynamic heading detection (HIGH) - COMPLETED
+    * ✅ Real-time status tracking with periodic updates (HIGH) - COMPLETED
+    * ✅ Intelligent save filename generation with 4-method fallback (MEDIUM) - COMPLETED
+    * 🚧 Professional message system with color-coded positioning (MEDIUM) - IN PROGRESS
+    * Multiple concurrent editing sessions support (MEDIUM)
+    * Enhanced DOM event system with 6 event types (LOW)
+    * Automatic section type detection (heading, code, list, etc) (LOW)
+    * Sophisticated section ID generation with hash-based algorithm (LOW)
 
 * **To Fix:**
-    * None currently identified
+    * Comprehensive status reporting dialog with detailed stats (HIGH)
+    * Floating global control panel with professional styling (MEDIUM)
+    * Enhanced setupSectionElement with comprehensive styling (LOW)
 
 * **To Refactor:**
-    * None currently identified
+    * ✅ stopEditing method with state preservation (CRITICAL) - COMPLETED
+    * ✅ getAllSections method for section collection management (MEDIUM) - COMPLETED
+    * ✅ hasChanges detection for unsaved modifications (HIGH) - COMPLETED
+    * ✅ updateGlobalStatus method with 2-second interval updates (MEDIUM) - COMPLETED
+    * ✅ handleSectionSplit for dynamic section reorganization (LOW) - COMPLETED
+    * ✅ checkForSectionSplits automatic heading detection (LOW) - COMPLETED
 
 * **To Remove:**
     * None currently identified