feat: add dockerized demo deployment

DEPLOYMENT.md

@@ -0,0 +1,85 @@
+# Demo Deployment
+
+This project can run behind the existing Caddy edge service with this temporary route:
+
+```text
+Caddy -> chatroom-nginx -> chatroom-app
+```
+
+The chatroom compose stack joins the existing external Docker network named `caddy_proxy`. No app ports are published to the host.
+
+## Start the Chatroom Stack
+
+From this project directory:
+
+```powershell
+docker compose up -d --build
+docker compose ps
+```
+
+Test the FastAPI health endpoint through the Nginx container:
+
+```powershell
+docker compose exec chatroom-nginx wget -qO- http://chatroom-app:8000/health
+```
+
+## Temporary Caddy Change
+
+Do this manually in:
+
+```text
+D:\Programing\Scripts\Home Lab\Interanet\caddy-deployment\config\caddy\Caddyfile
+```
+
+Add this temporary block:
+
+```caddy
+chat.amiirkhl.ir {
+    import {$CADDY_TLS_MODE:custom_tls}
+    reverse_proxy chatroom-nginx:80
+}
+```
+
+If the current custom certificate does not include `chat.amiirkhl.ir`, use this instead:
+
+```caddy
+chat.amiirkhl.ir {
+    import letsencrypt_tls
+    reverse_proxy chatroom-nginx:80
+}
+```
+
+Reload Caddy from the Caddy deployment directory:
+
+```powershell
+docker compose exec caddy caddy reload --config /etc/caddy/Caddyfile
+```
+
+## Browser Test
+
+Open:
+
+```text
+https://chat.amiirkhl.ir
+```
+
+Use two browser tabs, join the same room, and send messages both ways. The frontend builds its WebSocket URL from the current page, so HTTPS should connect with:
+
+```text
+wss://chat.amiirkhl.ir/ws/{room}/{user}
+```
+
+## Undo After the Demo
+
+1. Remove the `chat.amiirkhl.ir` block from the Caddyfile.
+2. Reload Caddy:
+
+```powershell
+docker compose exec caddy caddy reload --config /etc/caddy/Caddyfile
+```
+
+3. Stop and remove the chatroom stack from this project directory:
+
+```powershell
+docker compose down
+```