The seam's dunder-member test (added in the base seam PR) asserts
`DUNDER_MEMBER.test('____')` is true and `test('__')` is false, but the
regex `/^__.+__$/` rejected `____`: the `.+` demanded a non-empty middle,
while `____` is two adjacent `__` pairs with an empty middle. Widen to
`/^__.*__$/` so a name with distinct leading and trailing `__` pairs
matches whether or not it has a middle, and align the JSDoc. Regenerate
the cordis service catalog for the merged seam source line.