chore: Add E2E test helper scripts and API key management

Added helper scripts to make running E2E tests easier:

1. .env.example - Template for API key storage
2. run_e2e_with_env.py - Loads API key from .env and runs E2E test
3. monitor_e2e.py - Real-time monitoring script for live output
4. run_e2e_test.bat - Windows batch script for easy execution

These scripts make it easy to:
- Store API key securely in .env (already in .gitignore)
- Run E2E test without manually setting environment variables
- Monitor test progress in real-time

Usage:
  python run_e2e_with_env.py  # Background execution
  python monitor_e2e.py       # Live output in terminal

API key is stored in .env (not committed to git) and automatically
loaded by helper scripts.

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

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

.env.example

@@ -0,0 +1,6 @@
+# Atomizer Configuration Example
+# Copy this file to .env and fill in your API keys
+
+# Anthropic API Key for LLM Mode
+# Get your key from: https://console.anthropic.com/
+ANTHROPIC_API_KEY=your-api-key-here