literate: create org/render.org, org/theme.org, org/package.org

Follows the literate programming workflow:
  Overview → Contract → Tests → Implement → Tangle → Test (GREEN)

render.org covers render.lisp + render-tests.lisp (component protocol,
render dispatch, dirty propagation)
theme.org covers theme.lisp + theme-tests.lisp (theme class, presets,
color resolution)
package.org covers package.lisp (cl-tty.box defpackage)

org/package.org

@@ -0,0 +1,77 @@
+#+TITLE: Base Component Package
+#+STARTUP: content
+#+FILETAGS: :cl-tty:components:
+
+* Overview
+
+The ~cl-tty.box~ package is the central namespace for the component
+system. It aggregates all component-related symbols — box, text,
+dirty tracking, render dispatch, theme engine — under one package.
+
+Why ~box~ as the package name? Historically the package was created
+for the ~box~ and ~text~ renderables, and the name stuck as the
+package grew to encompass the entire component layer. The package
+~:use~s ~cl-tty.backend~ (for drawing primitives) and ~cl-tty.layout~
+(for layout nodes). All component code lives in this package.
+
+This org file is documentation-only: it explains the package design
+but the code itself is just a ~defpackage~ form.
+
+* Contract
+
+The ~cl-tty.box~ package exports these symbol groups:
+
+- Box: ~box~, ~make-box~, ~render-box~, border style/title accessors
+- Span: ~span~, span attribute readers
+- Text: ~text~, ~make-text~, ~render-text~, text accessors
+- Dirty: ~dirty-mixin~, ~dirty-p~, ~mark-clean~, ~mark-dirty~
+- Render: ~render~, ~render-screen~, ~render-node~, tree navigation
+- Theme: ~theme~, ~make-theme~, ~theme-color~, ~load-preset~,
+  ~define-preset~
+
+* Implementation
+
+~cl-tty.box~ uses ~cl-tty.backend~ for ~draw-text~, ~draw-border~,
+etc., and ~cl-tty.layout~ for ~layout-node~, ~compute-layout~, and the
+~vbox~/~hbox~ macros.
+
+The only direct dependencies are these two packages — no other
+application code is needed to define components.
+
+#+BEGIN_SRC lisp :tangle ../src/components/package.lisp
+(defpackage :cl-tty.box
+  (:use :cl :cl-tty.backend :cl-tty.layout)
+  (:export
+   ;; Box
+   #:box #:make-box
+   #:box-layout-node
+   #:box-border-style #:box-title #:box-title-align
+   #:box-fg #:box-bg
+   #:render-box
+   ;; Span
+   #:span
+   #:span-text #:span-bold #:span-italic #:span-underline
+   #:span-reverse #:span-dim #:span-fg #:span-bg
+   ;; Text
+   #:text #:make-text
+   #:text-layout-node #:text-content #:text-spans
+   #:text-fg #:text-bg #:text-wrap-mode
+   #:render-text
+   ;; Utilities (for tests)
+   #:word-wrap #:split-string
+   ;; Dirty tracking
+   #:dirty-mixin #:dirty-p #:mark-clean #:mark-dirty
+   ;; Rendering pipeline
+   #:render #:render-screen #:render-node
+   #:component-layout-node #:component-children #:component-parent
+   #:available-width #:available-height
+   #:propagate-dirty
+   ;; Theme engine
+   #:theme #:make-theme #:theme-mode
+   #:theme-color #:load-preset #:define-preset))
+(in-package :cl-tty.box)
+#+END_SRC
+
+The ~#:word-wrap~ and ~#:split-string~ exports are for tests only —
+they're utility functions used internally by ~text~ rendering but
+exposed so the test suite can unit-test them directly.