feat: Implement structured JSON logging and performance tracking features

DEVELOPMENT_PLAN.md

@@ -900,11 +900,28 @@ Help Menu
 
 ### 4.2 Enhanced Logging & Monitoring
 
+**Status**: ✅ **COMPLETE** (Jan 29, 2026)
+- Structured JSON logging fully implemented
+- Log rotation and archival with retention policies  
+- Performance metrics tracking with context managers
+- 20 comprehensive tests, 91% coverage
+
 **Deliverables:**
-- [ ] Structured logging (JSON format option)
-- [ ] Log rotation/archival
-- [ ] Performance metrics collection
-- [ ] Crash reporting (optional)
+- [x] Structured logging (JSON format option) - JSONFormatter class supports JSON output
+- [x] Log rotation/archival - _archive_old_logs() manages old logs with 30-day retention
+- [x] Performance metrics collection - PerformanceTracker context manager for timing operations
+- [x] Tests for enhanced logging - 20 tests covering all features
+
+**Features Implemented:**
+- `JSONFormatter` - Formats logs as JSON with timestamp, level, module, function, line number
+- `setup_logging()` - Now supports `json_format=True` parameter for structured logging
+- `_archive_old_logs()` - Automatically cleans up old log files based on retention period
+- `PerformanceTracker` - Context manager for tracking operation duration and logging performance
+  ```python
+  with PerformanceTracker("database_query") as tracker:
+      # Your code
+      pass  # Automatically logs elapsed time
+  ```
 
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