feat: update Dockerfile and workflow for environment variable support

- Modified the Dockerfile to include ARG and ENV for PUBLIC_CONVEX_URL and PUBLIC_CONVEX_SITE_URL, enhancing configuration flexibility.
- Updated the deploy workflow to pass these environment variables during the build process.
- Adjusted package.json to use bun for script commands and added svelte-adapter-bun for improved Svelte integration.

packages/backend/package.json

@@ -28,7 +28,6 @@
     "@types/ssh2": "^1.15.5",
     "better-auth": "catalog:",
     "convex": "catalog:",
-    "nodemailer": "^7.0.10",
-    "ssh2": "^1.17.0"
+    "nodemailer": "^7.0.10"
   }
 }