feat: AI Type Agent - vision-based Open Dental automation via Windows agent

Adds a Windows-side agent (screenshot/click/type over HTTP) plus backend
services to locate UI elements via vision and drive an existing-patient
appointment flow in Open Dental, wired into the Copy/Type Agent page and
socket progress updates.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/Backend/.env

@@ -4,6 +4,7 @@ PORT=5000
 CLOUDFLARE_HOST=
 FRONTEND_URLS=http://localhost:3000,https://local-summit.mydentalofficemanagement.com
 SELENIUM_AGENT_BASE_URL=http://localhost:5002
+WINDOWS_AGENT_TOKEN=dev-windows-agent-token
 JWT_SECRET = 'dentalsecret'
 LICENSE_SECRET=3aa4ab937e46c6863b9e3c2b591a595b31ea3af1060bf5e7961ad722a8b54f92
 DB_HOST=localhost