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/tests/tradfn.sx

@@ -18,6 +18,10 @@
 
 (define mksel (fn (v cs d) (list :select v cs d)))
 
+(define mktrap (fn (codes t c) (list :trap codes t c)))
+
+(define mkthr (fn (code msg) (list :throw code msg)))
+
 (apl-test
   "tradfn R←L+W simple add"
   (mkrv (apl-call-tradfn {:result "R" :omega "W" :stmts (list (mkasg "R" (mkdyd "+" (mknm "L") (mknm "W")))) :alpha "L"} (apl-scalar 5) (apl-scalar 7)))
@@ -125,3 +129,28 @@
   "tradfn :For factorial 1..5"
   (mkrv (apl-call-tradfn {:result "R" :omega "W" :stmts (list (mkasg "R" (mknum 1)) (mkfor "x" (mkmon "⍳" (mknm "W")) (list (mkasg "R" (mkdyd "×" (mknm "R") (mknm "x")))))) :alpha nil} nil (apl-scalar 5)))
   (list 120))
+
+(apl-test
+  "tradfn :Trap normal flow (no error)"
+  (mkrv (apl-call-tradfn {:result "R" :omega nil :stmts (list (mktrap (list 0) (list (mkasg "R" (mknum 99))) (list (mkasg "R" (mknum -1))))) :alpha nil} nil nil))
+  (list 99))
+
+(apl-test
+  "tradfn :Trap catches matching code"
+  (mkrv (apl-call-tradfn {:result "R" :omega nil :stmts (list (mktrap (list 5) (list (mkthr 5 "boom")) (list (mkasg "R" (mknum 42))))) :alpha nil} nil nil))
+  (list 42))
+
+(apl-test
+  "tradfn :Trap catch-all (code 0)"
+  (mkrv (apl-call-tradfn {:result "R" :omega nil :stmts (list (mktrap (list 0) (list (mkthr 99 "any")) (list (mkasg "R" (mknum 1))))) :alpha nil} nil nil))
+  (list 1))
+
+(apl-test
+  "tradfn :Trap catches one of many codes"
+  (mkrv (apl-call-tradfn {:result "R" :omega nil :stmts (list (mktrap (list 1 2 3) (list (mkthr 2 "two")) (list (mkasg "R" (mknum 22))))) :alpha nil} nil nil))
+  (list 22))
+
+(apl-test
+  "tradfn :Trap continues to next stmt after catch"
+  (mkrv (apl-call-tradfn {:result "R" :omega nil :stmts (list (mktrap (list 7) (list (mkthr 7 "c")) (list (mkasg "R" (mknum 10)))) (mkasg "R" (mkdyd "+" (mknm "R") (mknum 5)))) :alpha nil} nil nil))
+  (list 15))