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/scoreboard.json

@@ -3,13 +3,15 @@
     "structural": {"pass": 94, "fail": 0},
     "operators": {"pass": 117, "fail": 0},
     "dfn": {"pass": 24, "fail": 0},
-    "tradfn": {"pass": 20, "fail": 0},
+    "tradfn": {"pass": 25, "fail": 0},
     "valence": {"pass": 14, "fail": 0},
-    "programs": {"pass": 46, "fail": 0},
+    "programs": {"pass": 45, "fail": 0},
     "system": {"pass": 13, "fail": 0},
-    "idioms": {"pass": 34, "fail": 0}
+    "idioms": {"pass": 64, "fail": 0},
+    "eval-ops": {"pass": 14, "fail": 0},
+    "pipeline": {"pass": 40, "fail": 0}
   },
-  "total_pass": 362,
+  "total_pass": 450,
   "total_fail": 0,
-  "total": 362
+  "total": 450
 }