Add beautiful dashboard example with Catppuccin Mocha theme

Visually stunning system monitor dashboard demonstrating modern TUI
aesthetics: rounded borders, padding, Unicode indicators, sparkline
charts, metrics cards, and strong focus contrast using the Catppuccin
Mocha palette.

Components used: Menu, Chart, MetricsDashboard, ProgressBar, KeyHints,
Toast, and FocusManager for multi-panel navigation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ryanoneill

Cargo.toml

@@ -67,6 +67,10 @@ tokio-test = "0.4"
 name = "themed_app"
 required-features = ["input-components", "data-components", "display-components"]
 
+[[example]]
+name = "beautiful_dashboard"
+required-features = ["full"]
+
 [[example]]
 name = "component_showcase"
 required-features = ["full"]