--- description: Plan a new StemeDB milestone --- I need to plan a new milestone for StemeDB. Use the `stemedb-planner` agent. **Steps:** 1. **Context**: Read `stemedb/roadmap.md` and `stemedb/architecture.md`. 2. **Goal**: Ask the user which Milestone/Phase to plan. 3. **Structure**: Create the directory structure: `mkdir -p stemedb/roadmap/milestone-N/{...}`. 4. **Tasks**: Generate task definitions. **Focus**: - Ensure strict adherence to the "Spine -> Lattice -> Cortex" progression. - Prioritize **Traits** and **Types** before **Impls**.