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

src/components/input.lisp

@@ -1,4 +1,4 @@
-(in-package #:cl-tui.input)
+(in-package #:cl-tty.input)
 
 ;;; ---------------------------------------------------------------------------
 ;;; Utility: split-string (avoids external dependency)
@@ -301,7 +301,7 @@
 ;;; ---------------------------------------------------------------------------
 ;;; Backend integration
 ;;; ---------------------------------------------------------------------------
-(defmethod read-event ((b cl-tui.backend:backend) &key timeout)
+(defmethod read-event ((b cl-tty.backend:backend) &key timeout)
   (declare (ignore b))
   (when (probe-file "/dev/stdin")
     (%read-event :timeout timeout)))