Upgrade runtime to Go 1.25 and add container orchestration.

Add a cache-optimized multi-stage Dockerfile with non-root runtime, compose service definitions for local/dev execution, CI Go version alignment, and docs/path cleanup updates.

Made-with: Cursor

README.md

@@ -27,6 +27,26 @@ Optional environment variables:
 - `ADDR` (default `:8080`)
 - `ADMIN_PUBLIC_KEY` (bootstrap initial inviter/admin user)
 
+## Docker Compose
+
+Build and run the backend service:
+
+```bash
+docker compose up --build -d
+```
+
+Stop the service:
+
+```bash
+docker compose down
+```
+
+For local development with auto-rebuild on file changes:
+
+```bash
+docker compose up --watch
+```
+
 ## Frontend
 
 Open `web/index.html` through a static server (recommended) or browser file URL.