⚡ 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 -->

packages/bot-engine/apiHandlers/legacy/getOpenAIChatCompletionStream.ts

@@ -0,0 +1,58 @@
+import { decryptV2 } from '@typebot.io/lib/api/encryption/decryptV2'
+import { isNotEmpty } from '@typebot.io/lib/utils'
+import {
+  ChatCompletionOpenAIOptions,
+  OpenAICredentials,
+} from '@typebot.io/schemas/features/blocks/integrations/openai'
+import { SessionState } from '@typebot.io/schemas/features/chat/sessionState'
+import { OpenAIStream } from 'ai'
+import { parseVariableNumber } from '@typebot.io/variables/parseVariableNumber'
+import { ClientOptions, OpenAI } from 'openai'
+import { defaultOpenAIOptions } from '@typebot.io/schemas/features/blocks/integrations/openai/constants'
+import { getCredentials } from '../../queries/getCredentials'
+
+export const getOpenAIChatCompletionStream = async (
+  state: SessionState,
+  options: ChatCompletionOpenAIOptions,
+  messages: OpenAI.Chat.ChatCompletionMessageParam[]
+) => {
+  if (!options.credentialsId) return
+  const credentials = await getCredentials(options.credentialsId)
+  if (!credentials) {
+    console.error('Could not find credentials in database')
+    return
+  }
+  const { apiKey } = (await decryptV2(
+    credentials.data,
+    credentials.iv
+  )) as OpenAICredentials['data']
+
+  const { typebot } = state.typebotsQueue[0]
+  const temperature = parseVariableNumber(typebot.variables)(
+    options.advancedSettings?.temperature
+  )
+
+  const config = {
+    apiKey,
+    baseURL: options.baseUrl,
+    defaultHeaders: {
+      'api-key': apiKey,
+    },
+    defaultQuery: isNotEmpty(options.apiVersion)
+      ? {
+          'api-version': options.apiVersion,
+        }
+      : undefined,
+  } satisfies ClientOptions
+
+  const openai = new OpenAI(config)
+
+  const response = await openai.chat.completions.create({
+    model: options.model ?? defaultOpenAIOptions.model,
+    temperature,
+    stream: true,
+    messages,
+  })
+
+  return OpenAIStream(response)
+}