feat: Add start-dev.bat and improve app.py error reporting

Added Windows-optimized launcher:
- start-dev.bat: Simple batch file using npm run dev
  - Automatically kills processes on ports 3001 and 5173
  - Uses concurrently to run both services
  - Single window, simpler than Python launcher
  - Recommended for Windows users

Improved app.py:
- Better error output capture and display
- Increased wait time to 3 seconds
- Shows last 500 characters of error output

Windows users now have 3 options:
1. start-dev.bat (simplest - recommended)
2. python app.py (advanced with port management)
3. npm run dev (manual)

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

app.py

@@ -179,7 +179,7 @@ class AppLauncher:
             )
 
             # Wait a bit and check if process started successfully
-            time.sleep(2)
+            time.sleep(3)
 
             if self.backend_process.poll() is None:
                 self.print_success("Backend server started successfully")
@@ -187,6 +187,15 @@ class AppLauncher:
                 return True
             else:
                 self.print_error("Backend server failed to start")
+                # Try to read error output
+                if self.backend_process.stdout:
+                    try:
+                        output = self.backend_process.stdout.read()
+                        if output:
+                            print(f"\n{Color.FAIL}Error output:{Color.ENDC}")
+                            print(output[-500:] if len(output) > 500 else output)  # Last 500 chars
+                    except:
+                        pass
                 return False
 
         except Exception as e: