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/WindowsAgent/README.md

@@ -0,0 +1,59 @@
+# Dental Agent (Windows)
+
+`agent.py` runs on a staff front-desk Windows PC. It connects to the app's server over the
+`/agent` socket.io namespace and executes low-level commands — screenshot, click,
+double-click, type, key press — sent by the server. It has no knowledge of dental software
+or workflows; the app's AI reads the screenshots this agent sends back and decides what to
+click or type next.
+
+Not wired into the repo's root `npm install` on purpose — it targets Windows (`pyautogui`,
+`tkinter`) and doesn't need to install on every contributor's machine.
+
+## Command protocol
+
+Sent by the server, over the `/agent` namespace, as socket.io events with an ack callback:
+
+| Event              | Payload              | Ack response      |
+|---------------------|-----------------------|--------------------|
+| `cmd:screenshot`    | `{}`                  | `{ image: <base64 PNG> }` |
+| `cmd:click`         | `{ x, y }`            | `{ ok: true }`     |
+| `cmd:double_click`  | `{ x, y }`            | `{ ok: true }`     |
+| `cmd:double_click_current` | `{}`           | `{ ok: true }`     |
+| `cmd:type`          | `{ text }`            | `{ ok: true }`     |
+| `cmd:key`           | `{ key }`             | `{ ok: true }`     |
+
+Auth on connect: `{ auth: { token } }`, where `token` must match the server's
+`WINDOWS_AGENT_TOKEN`. The token is a constant baked into `agent.py` (`AGENT_TOKEN` near the
+top) — set it before building for a real office, staff never see or type it. The server tells
+front-desk PCs apart by connection IP address (shown on the Type Agent page), not anything
+the agent sends.
+
+## Local dev / testing
+
+```bash
+python3 -m venv .venv
+.venv/bin/pip install -r requirements.txt
+.venv/bin/python agent.py
+```
+
+On first run it asks only for the Server URL, then saves it to `agent_config.json` next to
+the script so it reconnects automatically after that. After that it has no window — just a
+system tray icon (green = Connected, gray = Connecting, red = Disconnected). Click it (or
+right-click for the same menu) for status, the server URL, "Settings..." (reopens the setup
+window pre-filled with the current URL — close without submitting to leave it unchanged), and
+Quit.
+
+`apps/Backend/scripts/fake-windows-agent.js` is a Node stand-in for this agent — useful for
+testing the server-side bridge without a Windows PC or a real screen to click on.
+
+## Building DentalAgent.exe
+
+Must be run **on Windows** (PyInstaller doesn't cross-compile):
+
+```bat
+py -m venv .venv
+.venv\Scripts\pip install -r requirements.txt
+.venv\Scripts\pyinstaller --onefile --windowed --name DentalAgent agent.py
+```
+
+Output: `dist\DentalAgent.exe`. Staff download and run it once — no other setup.