Feature request: Add Mistral Vibe CLI as a supported agent

[Woodman188]

idea / problem

The Mistral Vibe CLI is an open-source coding agent by Mistral, but it's not on Herdr's supported agent list. It runs fine in a pane as a plain terminal process, but gets no agent detection: no idle/working/blocked state in the sidebar, and herdr agent explain classifies the pane as a plain shell. There's no existing issue or manifest for it in the repo.

requested change

Add a detection manifest vibe.toml in src/detect/manifests/ (plus the copy in distribution/agent-detection/), following the same pattern as the existing 20+ manifests (grok.toml, cline.toml, qwen.toml, etc.). Details for the manifest:
Process name: vibe
Open source: https://github.com/mistralai/mistral-vibe
Install: via uv/pip; config lives in ~/.vibe/

why you want this

Why do you want this:
I (and others) run Vibe CLI as my daily coding agent. Herdr's persistence and detach/reattach already work for it, but without agent awareness the sidebar gives no overview of which Vibe session is working, blocked on input, or done — which is exactly the problem Herdr exists to solve.