User should be able to set "rules" (markdown content) for how an agent can use an MCP #265

Envisioning a simple text doc the user can save via settings modal along with a new MCP tool (like get_best_practices or something) so that agents using the MCP tools perform actions more like how the user would, according to how they are using Brainspread and the workflows they've implemented.

e.g. I log all of my meds, food, and supplements under a single block on my daily page with content "log", instead of just logging the blocks straight to my daily page, and sometimes I log specific things nested under a specific single block or I will just submit them chronologically. Using Brainspread via my Discord integration, which uses Brainspread's MCP, the agent does not have a way to understand much of the user's intent, so when I ask it to "log banana and glass of milk now", it might log the block in a location inconsistent with the user's usage patterns.