feat(tui): add full TUI dashboard mode with bubbletea

[CalvinAllen]

Summary

Add a dedicated TUI dashboard mode (dtvem tui or dtvem ui) providing a full-screen terminal interface for managing runtimes.

Proposed Features

Dashboard Overview

• Overview of all installed runtimes and versions
• Visual representation of global vs local configurations
• Real-time status display

Quick Actions

• Install new versions (with version browser)
• Uninstall versions
• Set global/local versions
• Switch between runtimes

Navigation

• Keyboard-driven navigation
• Tab/panel switching between runtimes
• Search/filter functionality

Implementation Notes

• Would be a separate command, not affecting existing CLI usage
• Should gracefully handle terminal resize
• Consider persistence of UI state/preferences

Recommended Libraries

From the Charm ecosystem:

• bubbletea - Full TUI framework
• bubbles - Reusable TUI components (lists, tables, text inputs)
• lipgloss - Styling (already in use from Add TUI styled output with lipgloss #104)

Related

• Add TUI styled output with lipgloss #104 - TUI styled output (prerequisite)
• feat(tui): add interactive TUI elements with charmbracelet/huh #105 - Interactive TUI elements