apl: :Trap exception machinery — Phase 7 complete (+5 tests, 450/450)

apl-throw raises a tagged ("apl-error" code msg) error.
apl-trap-matches? checks if codes list contains the error's code
(0 = catch-all, à la Dyalog).

Eval-stmt :trap clause wraps try-block with R7RS guard;
on match, runs catch-block; on mismatch, re-raises.
Bonus :throw AST node for testing.

test.sh + conformance.sh now load lib/r7rs.sx (for guard) and
include eval-ops + pipeline suites in scoreboard.

All Phase 7 unchecked items are now ticked.
Final scoreboard: 450/450 across 10 suites.

lib/apl/transpile.sx

@@ -276,6 +276,17 @@
           (let
             ((val (apl-eval-ast (nth stmt 1) env)))
             (apl-tradfn-eval-select val (nth stmt 2) (nth stmt 3) env)))
+        ((= tag :trap)
+          (let
+            ((codes (nth stmt 1))
+              (try-block (nth stmt 2))
+              (catch-block (nth stmt 3)))
+            (guard
+              (e
+                ((apl-trap-matches? codes e)
+                  (apl-tradfn-eval-block catch-block env)))
+              (apl-tradfn-eval-block try-block env))))
+        ((= tag :throw) (apl-throw (nth stmt 1) (nth stmt 2)))
         (else (begin (apl-eval-ast stmt env) env))))))
 
 (define