optimize title generation speed

[Moshiii]

I notice that the title-generation is block the response flow and become the bottle neck of response speed:

Problem
The chatbot API endpoint was experiencing severe performance issues with response times exceeding 84 seconds for new chat creation. The root cause was blocking title generation - the system waited for an LLM API call to generate a chat title before returning the stream response.

Solution
Made title generation non-blocking using a two-phase approach:
Generate a temporary title immediately from the first 60 characters of the user's message
Generate the LLM-based title asynchronously in the background and update when ready
This allows the chat stream to start immediately while the polished title is generated asynchronously.

Changes
lib/db/queries.ts
Added updateChatTitleById function to update chat titles after creation
app/(chat)/api/chat/route.ts
Replaced blocking await generateTitleFromUserMessage() with immediate temporary title generation
Added asynchronous real title generation that updates the chat when ready
Added imports for updateChatTitleById and getTextFromMessage

Performance Impact
Before: 19+ seconds (blocking on LLM title generation)
After: <1 second (immediate response with temporary title, real title updates in background)

[vercel]

@Moshiii is attempting to deploy a commit to the Templates Test vtest314 Team on Vercel.

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[Moshiii]

@shaper @rauchg @tomocchino @marcusschiesser Please review this response optimization-related PR

[Moshiii]

@MrAllgoodWilson what should I do to get it approved? Please advice.

[MrAllgoodWilson]

I approve