Add generated .pi-map.md and .pi-map.index.md files across the repository
so the project navigation maps are shared and versioned. These artifacts
are maintained by project_map_init/patch/validate and must be kept in
sync with source edits.
Note: .cache/ remains ignored (added in previous commit).
- Drop is_builtin column from tool_types table
- Remove built-in tool seeding from startup
- Remove is_builtin from API schemas and frontend types
- Update tool-types spec to reflect removal of built-in concept
- Add Alembic migration for column removal
- Update tests to work without built-in distinction