Print companion members one per line

[rochala]

Companion members were joined with ", " and emitted inline, unlike the Members section which gets a fenced block with one signature per line. For a type with a large companion (cats.effect.IO has ~100) that produced a single unreadable line that could not be grepped.

Render them the same way as Members: a scala-fenced block, one signature per line.

Before

**Companion members:** def ofInitLast[A](init: List[A], last: A): NonEmptyList[A], def fromReducible[F[_], A](fa: F[A])(implicit F: Reducible[F]): NonEmptyList[A], def of[A](head: A, tail: A*): NonEmptyList[A], …

After

**Companion members:**
```scala
def ofInitLast[A](init: List[A], last: A): NonEmptyList[A]
def fromReducible[F[_], A](fa: F[A])(implicit F: Reducible[F]): NonEmptyList[A]
def of[A](head: A, tail: A*): NonEmptyList[A]
```

Sample output in skills/cellar/SKILL.md updated to match.

Testing

./mill lib.test — 372/372 pass.

Note

Out of scope here: renderCompanion ignores --limit, unlike renderMembers, so a large companion still dumps in full — now as many lines rather than one long one.

🤖 Generated with Claude Code