fix(fk-cascade-guard): parse multiline relations, fingerprint baseline, oxfmt-clean output

Addresses CodeRabbit review on #4618:
- Reconstruct logical statements by balancing brackets so a relation whose
  onDelete/fields span multiple lines is no longer skipped.
- Match baseline entries on key + onDelete + ordered fkColumns, so changing a
  relation's FK column or flipping Cascade/SetNull re-triggers the guard instead
  of inheriting the old acceptance. Exit 2 on malformed baseline JSON/shape.
- Emit the baseline in oxfmt's format (inline short arrays) so regeneration stays
  code-quality clean.

Author: ericallam