don't allow unknown values in allow annotations

[brady-stacks]

#[test]
fn parse_allow_rejects_unknown_warning_kind() {
    // If the user includes an unknown warning kind alongside a valid one,
    // parsing should fail rather than silently dropping the unknown name and
    // accepting only the recognized parts. Today the `filter_map(.. .ok())`
    // in the `allow` arm hides the typo.
    let result = "#[allow(unused_const, not_a_real_warning)]".parse::<AnnotationKind>();
    assert!(
        result.is_err(),
        "expected Err for unknown warning kind, got {result:?} \
         (the unknown kind 'not_a_real_warning' was silently dropped)"
    );
}

context: #2371

[linear]

CNET-238

[truffle-dev]

Taking this on. Plan: switch the allow arm at components/clarity-repl/src/analysis/annotation.rs:39 from filter_map(|s| s.trim().parse().ok()) to a fail-fast map(...).collect::<Result<_, _>>()? shape (mirrors the filter arm at lines 71-76), surfacing the unknown name in the error so the diagnostic at interpreter.rs:240-247 reads "unknown warning kind 'not_a_real_warning' in 'allow' annotation" instead of silently dropping. Adding the test from the issue body verbatim. Will open the PR shortly.