129 reject panic dup name

// Test 210_129: MUST_FAIL — a branch name can't be both a panic branch
//                          (`| ?!oom`) and a required branch (`| oom`).
//
// `?!` is a KIND marker on a branch (like `?` optional), not a separate
// branch. Declaring `oom` twice — once as panic, once as required — is a
// duplicate-name error, same as declaring any branch twice. This pins that
// `?!` doesn't escape the duplicate-name check.
//
// Expected: parser rejects with PARSE003 "duplicate branch name 'oom'".

~pub event e { n: u32 }
| success u32
| ?!oom u32
| oom u32