Read the workflow thread for the planner's sense design: `nerve thread {{threadId}}`

Implement the sense. Create exactly:
1. The sense directory under {{sensesDir}}/<sense-name>/
2. index.js — export async function compute(db, _peers), import schema from "./schema.ts"
3. schema.ts — drizzle-orm/sqlite-core
4. migrations/0001_init.sql — must match schema.ts
5. Update {{nerveRoot}}/nerve.yaml — add sense config + reflex entry

Follow the patterns from existing senses. Create all files now.