Allow the API/MCP connector to delete or replace note content, not just append

Right now the official Capacities API/MCP connector (the one AI tools like Claude use) can only append content to a note — there's no way to delete or replace existing body content programmatically. This makes any AI-assisted revision workflow (correcting an outdated note, restructuring a batch of notes to a new format, etc.) much more manual than it needs to be: the new version gets appended at the bottom, and the old text has to be removed by hand in the app afterward, every single time.

I understand the safety reasoning behind restricting destructive write access from an API. Two ideas that could address that without keeping the current append-only limitation:

1. A granular, opt-in permission per connector/integration ("Allow delete/replace content"), off by default — anyone who doesn't enable it keeps today's safe append-only behavior.
2. Capacities already has version history (since Release 70), which acts as a safety net — an API-triggered delete/replace wouldn't be truly destructive, since any prior version could be restored. That existing feature already mitigates a lot of the risk the current restriction guards against.