Relocate all 64 R2dbc*Store implementations from dc3-common-{auth,manager,data,agentic} repositories into new dc3-db-postgres-{auth,manager,data,agentic} adapter modules (package io.github.pnoker.db.postgres.<domain>), each registered through its own AutoConfiguration. Reactive*Store ports and filter types stay in the business modules; services are untouched. Drops stale MyBatis wording from AGENTS.md and init runner javadoc.
