[AI-BUILDER-12] (frontend): chat readiness check for steps preview

[kevinkim-ogp]

TL;DR

Adds the readiness check to the frontend and only show the 'Preview steps' button if the chat message is deemed to be sufficient for the LLM to generate steps for the Pipe.

How to test?

• Should see the Preview steps button when the chat interface has reasonable information to generate steps
• Should not see the Preview steps button if the user input gibberish and the LLM is request for more information or does not have enough information to generate steps for a Pipe

[kevinkim-ogp]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [AI-BUILDER-15] PLU-605: chat feedback #1352
• [AI-BUILDER-14] feat: adds AI suggestions for form inputs #1364
• [AI-BUILDER-13] (frontend): refactor form modal content #1311
• [AI-BUILDER-12] (frontend): chat readiness check for steps preview #1363 👈 (View in Graphite)
• [AI-BUILDER-11] (frontend): preserve chat history and refactor #1365
• [AI-BUILDER-10] (backend): add chat readiness check #1362
• [AI-BUILDER-9] PLU-604 (frontend): Preview steps and create Pipe #1310
• [AI-BUILDER-8] PLU-603 (frontend): Chat interface #1309
• [AI-BUILDER-7] PLU-584 (backend): add api for chat streaming #1307
• [AI-BUILDER-6] PLU-584 (backend): setup api route #1306
• [AI-BUILDER-5] (frontend): add ai related deps #1305
• [AI-BUILDER-4]: create pipe from generated steps #1304
• [AI-BUILDER-3] (frontend): preview generated steps #1361
• [AI-BUILDER-2] PLU-595 (frontend): enter prompt #1303
• [AI-BUILDER-1] PLU-583 (backend): mutation to generate AI steps #1302
• [AI-2] PLU-583 (feat): add deps for AI and tracing #1360 : 1 other dependent PR (#1312 )
• [AI-1] (chore): bump zod and typescript #1359
• trunk/ai

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