fix(phase1): Critical security fixes - API key exposure, error handling

## Phase 1: Critical Security Fixes - COMPLETE

### 1. API Key Exposure (llm-extractor.ts)
- Replace console.log with structured logger calls
- Remove debug emojis from logs to prevent PII exposure
- Consolidated error messages for better security

### 2. Error Suppression (DevtoolsUtils.ts)
- Replaced blanket error suppression with conditional DEBUG mode
- Added logger integration for error visibility during development
- Documented rationale for selective error handling
- TODO: Implement selective error filtering for production

### 3. Fire-and-Forget Promises (PageCollector.ts)
- Enhanced catch block with contextual error logging
- Added logic to filter expected errors (Target closed)
- Improved error recovery during page cleanup

### Documentation
- Created CODE_QUALITY_IMPROVEMENT_PLAN.md (8-phase roadmap)
- Created QUALITY_IMPROVEMENT_STATUS.md (real-time progress tracker)

## Impact
- ✅ API keys no longer logged to console
- ✅ Better error visibility in DEBUG mode
- ✅ Improved error context in catch blocks
- ✅ Non-breaking changes, all tests passing

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

Author: ForgeFlow v2