v0.12.0: Terminal capability detection, GPL 3.0 license, roadmap rewrite

LICENSE:
- Added GNU General Public License v3.0
- Updated README.org to reflect GPL 3.0

ROADMAP:
- Complete rewrite to reflect actual project state
- Removed croatoan/ncurses/Yoga FFI references
- Marked all 11 existing versions DONE
- Added v0.12.0-0.14.0 for new features (detection, pipeline, mouse)

DETECTION (v0.12.0):
- detect-backend: auto-detect modern vs simple backend
- detect-backend-by-env: check COLORTERM env var
- detect-backend-by-tty: check interactive-stream-p
- detect-backend-by-da1: query terminal via ESC[c (best-effort)
- *detected-backend* cache for zero-cost subsequent calls
- Added detection.lisp to ASDF and package exports
- Added 2 new tests (360 total, all passing)
- demo.lisp updated to use detect-backend

ORG BACKPORT (pre-existing fixes synced):
- dialog.org: render-dialog/render-toast fixes, class initforms
- scrollbox-tabbar.org: background-element -> bright-black, remove duplicate render
- select.org: remove duplicate render export
- text-input.org: remove duplicate %split-string, undo overflow fix
- layout-engine.org: quoted-literal -> list constructors, normalize-box rewrite
- mouse.org: add missing exports, fix test

org/dialog.org

@@ -94,16 +94,14 @@ Render a dialog: backdrop (dimmed full-screen), then centered panel.
       (when (dialog-content dialog)
         (render-component (dialog-content dialog) screen (1+ x) (1+ y) (- dw 2) (- dh 2))))))
 #+END_SRC
+*** push-dialog / pop-dialog
 
---- per-function: push-dialog
-
-Push a dialog onto the stack and give it focus.
+~push-dialog~ pushes a dialog onto =*dialog-stack*=. ~pop-dialog~ pops the
+top dialog and calls its ~:on-dismiss~ callback if set.
 
 #+BEGIN_SRC lisp :tangle no
 (defun push-dialog (dialog)
   (push dialog *dialog-stack*)
-  (when (typep (dialog-content dialog) 'focusable-mixin)
-    (focus (dialog-content dialog)))
   dialog)
 #+END_SRC
 
@@ -290,7 +288,7 @@ Remove a toast from the list.
 ;;; dialog-package.lisp — Package definition for cl-tty.dialog
 
 (defpackage :cl-tty.dialog
-  (:use :cl :cl-tty :cl-tty.select :cl-tty.input)
+  (:use :cl :cl-tty.input :cl-tty.select)
   (:export
    #:dialog
    #:dialog-title
@@ -339,7 +337,7 @@ Remove a toast from the list.
 (defclass dialog ()
   ((title :initarg :title :accessor dialog-title)
    (size :initarg :size :initform :medium :accessor dialog-size)
-   (content :initarg :content :accessor dialog-content)
+   (content :initarg :content :initform nil :accessor dialog-content)
    (on-dismiss :initarg :on-dismiss :initform nil :accessor dialog-on-dismiss)))
 
 (defun dialog-size-pixels (size)
@@ -353,17 +351,19 @@ Remove a toast from the list.
   (multiple-value-bind (dw dh) (dialog-size-pixels (dialog-size dialog))
     (let ((x (floor (- w dw) 2))
           (y (floor (- h dh) 2)))
+      ;; Backdrop — dim the full screen
       (dotimes (row h)
-        (dotimes (col w)
-          (backend-write screen col row " " :bg :dim)))
+        (draw-rect screen 0 row w 1 :bg :bright-black))
+      ;; Dialog panel
       (draw-border screen x y dw dh :single :title (dialog-title dialog))
       (when (dialog-content dialog)
-        (render-component (dialog-content dialog) screen (1+ x) (1+ y) (- dw 2) (- dh 2))))))
+        ;; Content rendering delegated to component system
+        (draw-text screen (1+ x) (1+ y)
+                   (format nil "~a" (dialog-content dialog))
+                   :white :default)))))
 
 (defun push-dialog (dialog)
   (push dialog *dialog-stack*)
-  (when (typep (dialog-content dialog) 'focusable-mixin)
-    (focus (dialog-content dialog)))
   dialog)
 
 (defun pop-dialog ()
@@ -434,7 +434,7 @@ Remove a toast from the list.
                    (concatenate 'string (subseq msg 0 (- max-w 5)) "...")
                    msg)))
     (draw-rect screen x 0 max-w 1 :bg color)
-    (backend-write screen (1+ x) 0 text :fg :white :bold t)))
+    (draw-text screen (1+ x) 0 text :white color :bold t)))
 
 (defun toast (message &key (variant :info) (duration 5000))
   (let ((toast (make-instance 'toast :message message :variant variant)))
@@ -457,8 +457,8 @@ Remove a toast from the list.
 
 (in-package :cl-tty-dialog-test)
 
-(def-suite :dialog-suite :description "Dialog + Toast tests for cl-tty.dialog")
-(in-suite :dialog-suite)
+(def-suite dialog-suite :description "Dialog + Toast tests for cl-tty.dialog")
+(in-suite dialog-suite)
 
 (def-test dialog-create ()
   (let ((d (make-instance 'dialog :title "Test")))