cl: Phase 4 CLOS complete — generic functions, multi-dispatch, method qualifiers, 437/437 tests

- lib/common-lisp/clos.sx (27 forms): class registry (8 built-in classes),
  defclass/make-instance/slot-value/slot-boundp/change-class, defgeneric/defmethod
  with :before/:after/:around, clos-call-generic (standard combination: sort by
  specificity, fire befores, call primary chain, fire afters reversed),
  call-next-method/next-method-p, with-slots, deferred accessor installation
- lib/common-lisp/tests/clos.sx: 41 tests (class-of, subclass-of?, defclass,
  make-instance, slot ops, inheritance, method specificity, qualifiers, accessors,
  with-slots, change-class)
- lib/common-lisp/tests/programs/geometry.sx: 12 tests — intersect generic
  dispatching on geo-point×geo-point, geo-point×geo-line, geo-line×geo-line,
  geo-line×geo-plane (multi-dispatch by class precedence)
- lib/common-lisp/tests/programs/mop-trace.sx: 13 tests — :before/:after
  tracing on area and describe-shape generics, call-next-method in circle/rect
- eval.sx: dynamic variables — cl-apply-dyn saves/restores global slot for
  specials; cl-mark-special!/cl-special?/cl-dyn-unbound; defvar now marks
  specials; let/let* rebind via cl-apply-dyn; 8 new tests (182 eval total)
- conformance.sh + test.sh: Phase 4 suites wired in
- plans/common-lisp-on-sx.md: Phase 4 + dynamic variable boxes ticked

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/common-lisp/conformance.sh

@@ -91,6 +91,18 @@ run_suite "Phase 3: interactive-debugger" \
   "lib/common-lisp/runtime.sx lib/common-lisp/tests/programs/interactive-debugger.sx" \
   "debugger-passed" "debugger-failed" "debugger-failures"
 
+run_suite "Phase 4: CLOS" \
+  "lib/common-lisp/runtime.sx lib/common-lisp/clos.sx lib/common-lisp/tests/clos.sx" \
+  "passed" "failed" "failures"
+
+run_suite "Phase 4: geometry" \
+  "lib/common-lisp/runtime.sx lib/common-lisp/clos.sx lib/common-lisp/tests/programs/geometry.sx" \
+  "geo-passed" "geo-failed" "geo-failures"
+
+run_suite "Phase 4: mop-trace" \
+  "lib/common-lisp/runtime.sx lib/common-lisp/clos.sx lib/common-lisp/tests/programs/mop-trace.sx" \
+  "mop-passed" "mop-failed" "mop-failures"
+
 echo ""
 echo "=== Total: $TOTAL_PASS passed, $TOTAL_FAIL failed ==="