Hyperscript: focus command, diagnostic test output, blur keyword

Parser/compiler/runtime for focus command. Tokenizer: focus, blur,
precedes, follows, ignoring, case keywords. Test spec: per-test
failure output for diagnosis.

374/831 (45%)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/hyperscript/compiler.sx

@@ -1061,6 +1061,8 @@
                     (list (quote nil?) t)
                     (list (quote set!) t v))))
               ((= head (quote halt!)) (list (quote hs-halt!) (nth ast 1)))
+              ((= head (quote focus!))
+                (list (quote dom-focus) (hs-to-sx (nth ast 1))))
               (true ast))))))))
 
 ;; ── Convenience: source → SX ─────────────────────────────────