fix(analyze): accept self-closing Match branches

[lntutor]

Summary

• recognize self-closing <Match when={...} /> elements as valid direct children of <Case>
• retain diagnostics for non-Match children
• add focused regression coverage

Context

The broader Case child validation from issue #39 was merged in #58 while this PR was open. That implementation accepted only JsxElement children, so valid self-closing Match branches were reported by askr/control-contract. This rebased PR now contains only the remaining compatibility fix.

Validation

• focused analyzer suite: 15/15 tests
• full npm run check: lint, typecheck, 202 tests with coverage, build, publint, and package dry-run

[lntutor]

Rebased onto current main after #58 merged. This PR is now a focused fix for the remaining analyzer bug: valid self-closing <Match when={...} /> children were still diagnosed under <Case>. The full repository check passes (202 tests, lint, typecheck, coverage, build, publint, package dry-run).

[lntutor]

Merged current upstream main into this branch without rewriting history. The conflict was additive in tests/analyze.rules.test.ts; the resolution preserves all upstream analyzer tests and retains the focused self-closing <Match /> regression test. Verified exact pushed head 4dc737c5a6aae815a6112ef9588cae283f325d18 with the focused regression test (1 passed) and full npm run check under Node 24.17.0 (lint, typecheck, 210 coverage tests, build, publint, and package dry-run all passed). GitHub now reports the PR mergeable; fresh CI is running.

[lntutor]

Current head 4dc737c5a6aae815a6112ef9588cae283f325d18 now appears to be in a clean merge-ready state: the PR is mergeable, all visible CI jobs on that exact SHA have completed successfully, and there are no review threads or review-body comments open on the current PR state. The self-closing <Match /> regression remains isolated to the intended analyzer case, with the upstream main test additions preserved on this head. If this still matches the intended direction, it looks ready for maintainer review/merge when convenient.