v0.2.0: Dirty tracking — dirty-mixin, mark-clean, mark-dirty

- dirty-mixin class with dirty slot (initform t)
- mark-clean clears dirty flag
- mark-dirty sets dirty flag
- 3 tests: default-dirty, clean, dirty-cycle
- ROADMAP.org: v0.2.0 all tasks DONE
- 31 component tests, 100% GREEN

src/components/dirty-tests.lisp

@@ -0,0 +1,20 @@
+;; Dirty tracking tests are in box-tests.lisp (same test suite)
+(in-package :cl-tui-box-test)
+
+(test dirty-mixin-default-is-dirty
+  "A dirty-mixin starts as dirty"
+  (let ((c (make-instance 'dirty-mixin)))
+    (is-true (dirty-p c) "new component should be dirty")))
+
+(test mark-clean-clears-dirty
+  "mark-clean sets dirty to nil"
+  (let ((c (make-instance 'dirty-mixin)))
+    (mark-clean c)
+    (is-false (dirty-p c) "after mark-clean, should not be dirty")))
+
+(test mark-dirty-sets-dirty
+  "mark-dirty sets dirty to t"
+  (let ((c (make-instance 'dirty-mixin)))
+    (mark-clean c)
+    (mark-dirty c)
+    (is-true (dirty-p c) "after mark-dirty, should be dirty again")))