feat: Add Python launcher script for easy application startup

Added comprehensive application launcher:
- app.py - Python script to start both backend and frontend
- start.bat - Windows batch file wrapper
- START_HERE.md - Quick start guide with troubleshooting
- Updated package.json with 'npm start' command

Features:
✅ Pre-flight checks (Node.js, npm, dependencies, .env)
✅ Starts both backend (port 3001) and frontend (port 5173)
✅ Colored terminal output with status messages
✅ Process monitoring and health checks
✅ Graceful shutdown with Ctrl+C
✅ Cross-platform support (Windows/Linux/Mac)
✅ Automatic cleanup of child processes

Usage:
  python app.py
  OR
  npm start
  OR (Windows only)
  start.bat

Benefits:
- Single command to start entire application
- No need for multiple terminal windows
- Automatic error detection and reporting
- User-friendly colored output
- Test account information displayed on startup
- Easy for non-technical users

Documentation:
- START_HERE.md provides complete quick start guide
- Includes troubleshooting section
- Lists all access points and test accounts

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

start.bat

@@ -0,0 +1,24 @@
+@echo off
+REM 5 Why Root Cause Analyzer - Windows Launcher
+REM Version: 1.0.0
+
+echo.
+echo ======================================================================
+echo   5 Why Root Cause Analyzer - v1.0.0
+echo   Starting application...
+echo ======================================================================
+echo.
+
+REM Check if Python is installed
+python --version >nul 2>&1
+if %errorlevel% neq 0 (
+    echo [ERROR] Python is not installed or not in PATH
+    echo Please install Python 3.7+ from https://www.python.org/
+    pause
+    exit /b 1
+)
+
+REM Run the Python launcher
+python app.py
+
+pause