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

docs/ARCHITECTURE.org

@@ -1,10 +1,10 @@
-#+TITLE: cl-tui Architecture
+#+TITLE: cl-tty Architecture
 #+STARTUP: content
-#+FILETAGS: :project:cl-tui:architecture:
+#+FILETAGS: :project:cl-tty:architecture:
 
 * Architecture
 
-cl-tui is a layered framework. Each layer has a single responsibility
+cl-tty is a layered framework. Each layer has a single responsibility
 and communicates with adjacent layers through a well-defined protocol.
 
 ** Layer Diagram
@@ -264,9 +264,9 @@ reads terminal background color at startup.
 ** File Structure
 
 #+BEGIN_SRC
-  cl-tui/
-  ├── cl-tui.asd
-  ├── cl-tui-tests.asd
+  cl-tty/
+  ├── cl-tty.asd
+  ├── cl-tty-tests.asd
   ├── README.org
   ├── LICENSE
   ├── docs/

docs/ROADMAP.org

@@ -1,6 +1,6 @@
-#+TITLE: cl-tui Roadmap
+#+TITLE: cl-tty Roadmap
 #+STARTUP: content
-#+FILETAGS: :docs:roadmap:cl-tui:
+#+FILETAGS: :docs:roadmap:cl-tty:
 
 * The Roadmap
 
@@ -87,7 +87,7 @@ the patch version (v0.X.Y).
 When a version ships:
 1. ~ROADMAP.org~ — mark item DONE, update LOGBOOK timestamp
 2. ~README.org~ — update Status line
-3. ~cl-tui.asd~ — update version string
+3. ~cl-tty.asd~ — update version string
 
 ** v0.1.0: Layout Engine
 
@@ -295,7 +295,7 @@ never hex values.
 8 presets: default (gold), professional, minimal, nord, tokyonight, catppuccin, monokai, gruvbox
 - Each preset is a plist: ~(:primary "#FFD700" :error "#BF616A" ...)~
 - ~(theme-load :nord)~ — activates a preset, re-renders dirty
-- Load from ~/.config/cl-tui/themes/<name>.lisp~ for custom themes
+- Load from ~/.config/cl-tty/themes/<name>.lisp~ for custom themes
 - ~80 lines
 
 *** TODO Dark/light variants