[Feature Request] Add MistralVibe & KiloCode to default agents

Add (native) support for:

- Mistral Vibe CLI https://github.com/mistralai/mistral-vibe
+ I managed to create the entry manually, but asking a question in the chat just ran forever

- KiloCode CLI https://kilo.ai/docs/code-with-ai/platforms/cli
+ I created the config (pointing to `kilo acp` command), but I get an error (`failed to connect: ACP connection closed`) when starting the agent

Start by examining how default agents are declared and how ACP connections are launched, then use the linked Mistral Vibe and KiloCode documentation to reproduce both reports. Test Mistral Vibe without the chat hanging and KiloCode with the `kilo acp` command. Done means both agents are available by default and can start and answer through the extension.

Written by the indexing model from the issue text.