Support for versioned subfolders in migrations

Description: Currently, the Supabase CLI only supports a flat directory structure for migration files within the migrations folder. All files must exist directly under supabase/migrations/ and follow a strict naming convention: <timestamp>_<name>.sql Problem In many projects — especially larger teams and long-term projects — it is preferred to organize migrations into versioned or release-based subfolders. This offers several benefits: • Improved clarity on which migrations belong to which release. • Clear separation between work-in-progress changes and already deployed releases. • Simplifies working with Git, release tagging, and CI/CD pipelines, as migrations can be directly linked to version numbers. Example structure Current Limitation Even though schema_paths can be configured in config.toml, this setting does not support structured migrations in subfolders, nor does it work with migrations stored outside the main migrations/ fold…