subagenttasks

Extend agent-schema-drift to cover D1 primitive schemas, not just AgentConfig

agent_schema_drift.py currently only cross-checks agent.rs/schema.ts/schema.py/schema.java for the AgentModel/AgentConfig/EffortLevel enums (confirmed clean this session: 5 enums, 27 plugin agent frontmatter files all in sync). It has no check for drift between a D1 primitive's actual table schema (e.g. workers/subagentroles/migrations/0001_init.sql) and the TypeScript types the worker's own src/index.ts assumes. Add a second check mode that diffs a migration's CREATE TABLE columns against the fields referenced in that worker's api handler.