Migration 0040 dropped token_info values that were not objects before
clearing the plaintext column. Objects stored as JSON strings are now
decoded, and other values are kept in the envelope under
legacy_token_info so downgrade restores them.
Main's access model (team editors and viewers, edit_credentials, owner-only
OAuth servers, per-user tool preferences, resource sponsors) now applies to
connection-backed tools and sources. Our migrations are renumbered to
0040_connections and 0041_connection_account_name, after main's
0038_resource_access_settings and 0039_resource_sponsors.
Where the two sides met: MCP tools save and load their connections as the
tool owner, editors may add a key (a new connection on the owner's account)
but never rewrite an existing connection's secret, fixed values stay
owner-only, and a member's own connection is used in member mode.