⚡ Introduce a new high-performing standalone chat API (#1200)

Closes #1154

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
	- Added authentication functionality for user sessions in chat API.
- Introduced chat-related API endpoints for starting, previewing, and
continuing chat sessions, and streaming messages.
- Implemented WhatsApp API webhook handling for receiving and processing
messages.
- Added environment variable `NEXT_PUBLIC_CHAT_API_URL` for chat API URL
configuration.

- **Bug Fixes**
	- Adjusted file upload logic to correctly determine the API host.
	- Fixed message streaming URL in chat integration with OpenAI.

- **Documentation**
- Updated guides for creating blocks, local installation, self-hosting,
and deployment to use `bun` instead of `pnpm`.

- **Refactor**
	- Refactored chat API functionalities to use modular architecture.
- Simplified client log saving and session update functionalities by
using external functions.
	- Transitioned package management and workflow commands to use `bun`.

- **Chores**
- Switched to `bun` for package management in Dockerfiles and GitHub
workflows.
	- Added new Dockerfile for chat API service setup with Bun framework.
	- Updated `.prettierignore` and documentation with new commands.

- **Style**
	- No visible changes to end-users.

- **Tests**
	- No visible changes to end-users.

- **Revert**
	- No reverts in this release.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

apps/builder/next.config.mjs

@@ -21,6 +21,12 @@ const injectViewerUrlIfVercelPreview = (val) => {
       process.env.VERCEL_BUILDER_PROJECT_NAME,
       process.env.NEXT_PUBLIC_VERCEL_VIEWER_PROJECT_NAME
     )
+  if (process.env.NEXT_PUBLIC_CHAT_API_URL.includes('{{pr_id}}'))
+    process.env.NEXT_PUBLIC_CHAT_API_URL =
+      process.env.NEXT_PUBLIC_CHAT_API_URL.replace(
+        '{{pr_id}}',
+        process.env.VERCEL_GIT_PULL_REQUEST_ID
+      )
 }
 
 injectViewerUrlIfVercelPreview(process.env.NEXT_PUBLIC_VIEWER_URL)