Fix spec creation failing for long summaries and other overflowing text columns

Fixed spec creation failing in production for summaries between 256 and 280 characters. The specs.summary column was created as varchar(255) while Spec.changeset allowed up to 280, so validated values still crashed with PostgreSQL 22001 (string_data_right_truncation) and surfaced to MCP clients as “the connector’s server isn’t responding”. The same latent bug was fixed for projects.description, drops.title, and drops.external_id (all widened from varchar(255) to text). varchar(255) → text is a metadata-only change, so migrations deploy safely via the migrate initContainer.