W14: C9 eliminate empty suite labels (test-only) — section E complete

The finding ("spec suites print with empty suite label") was six files
wide: test-chars (43 suite-less top-level deftests), test-import-bind
(14), test-ports (12), test-let-match (8), test-math (deftests NESTED in
deftests — every test reported as " > sin"), and 4 stray deftests between
suites in test-hyperscript-conformance.

Fixes: file-level defsuite wraps for the four flat files (mechanical wrap,
sx_validate-checked); test-math restructured deftest->defsuite ("math >
string->number"); hs strays wrapped in suites named for their section
comments (hs-compat-blockLiteral/cookies/some/where). The two
baseline-visible identities are renamed in spec/tests/known-failures.txt
in this same commit — the F10 gate enforces exactly this coupling.

Full baseline gate validated GREEN: 5798p/273f, fail set identical
(the -2 passes are the two wrapper deftests that no longer self-report
a vacuous PASS around their children).

Test-only: no semantics edits, no push.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

spec/tests/test-let-match.sx

@@ -1,3 +1,5 @@
+(defsuite "let-match"
+
 ;; Tests for let-match — CEK special form and bytecode compiler desugaring
 ;; let-match destructures a dict: (let-match {:key var} expr body...)
 
@@ -45,3 +47,5 @@
   (let-match {:a a :b b} (dict :a (+ 1 2) :b (* 3 4))
     (assert= a 3)
     (assert= b 12)))
+
+)