fix(parser): allow try in match subjects

[akonwi]

Summary

• parse a leading try expression directly in match-subject position
• preserve existing struct-literal versus match-arms disambiguation
• reject try catch handlers in match subjects with a targeted diagnostic because their block is ambiguous with the match arms
• cover catchless try subjects, parenthesized struct subjects, and rejected simple, qualified, and block catch handlers

Example

match try get_result() {
  5 => 1,
  _ => 0,
}

Catch handlers must be applied before matching rather than attached directly to the match subject.

Validation

• cd compiler && go test ./parse -run 'TestTryMatchSubjectSyntax|TestTryKeyword|TestBreakInMatchArms|TestMatchingOnEnums|TestMutOperandInSubjectPositions' -count=1
• cd compiler && go test ./... -count=1
• git diff --check

Fixes #334

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Project	Deployment	Actions	Updated (UTC)
ard-lang-dev	Ready	Preview, Comment	Jul 22, 2026 7:14pm