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/text-input.org

@@ -1307,14 +1307,15 @@ onto the redo stack, and restores the old value. ~textarea-redo~ does
 the reverse.
 
 The ~(>= (length stack) (array-total-size stack))~ guard prevents the
-stack from growing beyond 100 entries by resetting it.
+stack from growing beyond 100 entries by dropping the oldest entry.
 
 #+BEGIN_SRC lisp
 (defun textarea-push-undo (ta)
   (let ((stack (textarea-undo-stack ta)))
     (when (>= (length stack) (array-total-size stack))
-      (setf (textarea-undo-stack ta)
-            (make-array 100 :fill-pointer 0)))
+      (loop for i from 1 below (length stack)
+            do (setf (aref stack (1- i)) (aref stack i)))
+      (decf (fill-pointer stack)))
     (vector-push (textarea-value ta) stack)
     (setf (fill-pointer (textarea-redo-stack ta)) 0)))
 
@@ -2050,17 +2051,6 @@ experience; this section is what actually generates the compilable code.
 #+BEGIN_SRC lisp :tangle ../src/components/textarea.lisp
 (in-package #:cl-tty.input)
 
-;;; ---------------------------------------------------------------------------
-;;; Utility: split string (local copy for dependency-free operation)
-;;; ---------------------------------------------------------------------------
-(defun %split-string (string separator)
-  "Split STRING at each occurrence of SEPARATOR. Returns list of strings."
-  (loop with start = 0
-        for pos = (position separator string :start start)
-        collect (subseq string start pos)
-        while pos
-        do (setf start (1+ pos))))
-
 ;;; ---------------------------------------------------------------------------
 ;;; Textarea class
 ;;; ---------------------------------------------------------------------------
@@ -2219,10 +2209,10 @@ experience; this section is what actually generates the compilable code.
   "Save current value on undo stack."
   (let ((stack (textarea-undo-stack ta)))
     (when (>= (length stack) (array-total-size stack))
-      (setf (textarea-undo-stack ta)
-            (make-array 100 :fill-pointer 0)))
+      (loop for i from 1 below (length stack)
+            do (setf (aref stack (1- i)) (aref stack i)))
+      (decf (fill-pointer stack)))
     (vector-push (textarea-value ta) stack)
-    ;; Clear redo stack on new action
     (setf (fill-pointer (textarea-redo-stack ta)) 0)))
 
 (defun textarea-undo (ta)