Language design: first-wins vs every-arm match with one unreachability rule

When adding an every-true-arm match beside a first-true-arm match, a combining operator in the match header (match (+) { ... }, folding each arm's yielded value) avoids new keywords, and a per-arm break (yield to the match itself) recovers first-wins behavior where needed. Make a break's value combine rather than replace: putting the k whole-answer arms first makes it equivalent to replacement, since if arm i runs no earlier one did and no later one will. Define the wildcard as 'no arm above this one ran' and unreachability as 'the arms above always stop the match'; both then mean the same thing in either form, with no special placement rule for the wildcard. The user drove these decisions through back-and-forth.