V121: Widen phoenix_kit_annotations_kind_check for the new "line" kind.

Etcher gains a simple two-endpoint line annotation alongside dimension — same geometry ({a: [x, y], b: [x, y]}) but no arrowheads and no inline numeric label. Title + comment ride the same composer flow as rectangle / circle / polygon.

Idempotent: each ADD CONSTRAINT is preceded by DROP CONSTRAINT IF EXISTS on the same prefixed table.