v0.1.0: Layout primitives + composable API — 23 new tests

Layout primitives (org/layout-primitives.org, ~290 lines):
- CLOS layout-node class wrapping YGNodeRef with tg:finalize for GC cleanup
- 12 setter functions with keyword→integer enum translation
- layout-calculate: runs Yoga layout, returns root
- 14 tests: dimension, direction, flex-grow, align, justify,
  padding, margin, absolute position, wrap, gap, nested layout

Composable API (org/layout-composable.org, ~200 lines):
- vbox/hbox macros: declarative container creation with style props
- overlay macro: absolute-positioned child over relative base
- spacer function: flex-grow filler
- make-props-list helper: extracts plist minus :children
- 6 tests: vbox stacking, hbox layout, spacer flex, overlay position,
  align/justify via vbox, padding offset

GREEN: 29/29 pass (59 assertions)
- yoga-ffi: 9 tests (22 assertions)
- layout-primitives: 14 tests (24 assertions)
- layout-composable: 6 tests (13 assertions)

cl-tui.asd

@@ -4,6 +4,8 @@
   :version "0.1.0"
   :license "AGPLv3"
   :description "Reusable Common Lisp Terminal UI Framework"
-  :depends-on (:cffi :croatoan)
+  :depends-on (:cffi :croatoan :trivial-garbage)
   :serial t
-  :components ((:file "lisp/yoga-ffi")))
+  :components ((:file "lisp/yoga-ffi")
+               (:file "lisp/layout-primitives")
+               (:file "lisp/layout-composable")))