zgbrenner adds a does-my-key-actually-work button

Connecting an AI account to Mike means pasting in an API key, and until now there was no way to know if you'd done it right short of trying a real task and watching it fail. zgbrenner's fork closes that gap. The settings page - newly relabelled from "AI Preferences" to "Connect AI Accounts" - now puts a Test Connection button next to each provider. Click it and the fork fires off a tiny, cheap request behind the scenes, then shows a green "Connection works" or a red error right there on the page.

The smart bit is the error. Instead of a generic "something went wrong," it passes the provider's own message straight through - things like "invalid authentication" or "insufficient quota" - so a non-technical user can actually tell whether they fat-fingered the key or ran out of credit.