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.

.github/workflows/deploy.yml

@@ -31,4 +31,7 @@ jobs:
           # Make sure to replace with your own namespace and repository
           tags: |
             killercf/sgc:latest 
-          platforms: linux/amd64     
+          platforms: linux/amd64
+          build-args: |
+            PUBLIC_CONVEX_URL=${{ secrets.PUBLIC_CONVEX_URL }}
+            PUBLIC_CONVEX_SITE_URL=${{ secrets.PUBLIC_CONVEX_SITE_URL }}