Rename cl-tui -> cl-tty, v0.9.0: Dialog System + Toast

Rename: cl-tty avoids naming collision with Quicklisp's cl-tui (naryl/cl-tui,
a cl-charms-based ncurses library). Our project is pure escape-sequence CL.

v0.9.0 adds:
- Dialog base class: modal overlay with backdrop, centered panel, size
  variants (:small/:medium/:large), stack-based management
- Dialog subclasses: alert, confirm, select-dialog, prompt-dialog
- Toast notifications: transient, top-right corner, auto-dismiss,
  colored variants (info/success/warning/error)
- 78 tests total, 100% passing

ASDF: read-time package references (+fiveam:+) replaced with
find-symbol so .asd loads without FiveAM pre-loaded

org/box-renderable.org

@@ -1,6 +1,6 @@
-#+TITLE: cl-tui Box Renderable — v0.2.0
+#+TITLE: cl-tty Box Renderable — v0.2.0
 #+STARTUP: content
-#+FILETAGS: :cl-tui:components:v0.2.0:
+#+FILETAGS: :cl-tty:components:v0.2.0:
 #+OPTIONS: ^:nil
 
 * Box Renderable
@@ -27,10 +27,10 @@ A Box has a =layout-node= slot for positioning via the layout engine. Its
 ** Tests
 
 #+BEGIN_SRC lisp
-(defpackage :cl-tui-box-test
-  (:use :cl :fiveam :cl-tui.backend :cl-tui.layout)
+(defpackage :cl-tty-box-test
+  (:use :cl :fiveam :cl-tty.backend :cl-tty.layout)
   (:export #:run-tests))
-(in-package :cl-tui-box-test)
+(in-package :cl-tty-box-test)
 
 (def-suite box-suite :description "Box renderable tests")
 (in-suite box-suite)
@@ -116,7 +116,7 @@ A Box has a =layout-node= slot for positioning via the layout engine. Its
 ** Implementation
 
 #+BEGIN_SRC lisp
-(in-package :cl-tui.box)
+(in-package :cl-tty.box)
 
 (defclass box ()
   ((layout-node :initform (make-layout-node) :accessor box-layout-node