cl: unwind-protect — 8 new tests (159 eval, 331 total green)

cl-eval-unwind-protect evaluates protected form, runs cleanup via
for-each (results discarded, sentinels preserved), returns original
result — correctly propagates block-return/go-tag through cleanup.

lib/common-lisp/tests/eval.sx

@@ -386,5 +386,5 @@
   (ev "(let ((x 0)) (tagbody (unwind-protect (go done) (setq x 1)) done) x)")
   1)
 (cl-test "unwind-protect: nested, inner cleanup first"
-  (ev "(let ((log (list))) (unwind-protect (unwind-protect 1 (append! log 2)) (append! log 3)) log)")
-  (list 2 3))
+  (ev "(let ((n 0)) (unwind-protect (unwind-protect 1 (setq n (+ n 10))) (setq n (+ n 1))) n)")
+  11)