Implement more dynamic TUI menu index for future additions

[csd113]

Current home page stays as is outside of the addition of the menu option

need on the main screen is one key:
[M] Menu

this brings you to an index menu for selecting more options

RustChan Menu

Home
Logs

Doctor
Tor
Network
Site
Settings
Diagnostics
Help

Check config, paths, ports, TLS, Tor, favicon, and runtime safety.

[↑↓] Navigate [Enter] Open [Esc] Back [Q] Quit

the > should slowly blink to let the user know their terminal is not frozen

controls: [↑↓] Select (I would also support Vim-style keys quietly: j = down k = up) [Enter] Open [Esc] Back [Q] Quit

Main dashboard stays current/simple.
Press M to open the vertical menu.
Use ↑ / ↓ to select a page.
Press Enter to open.
Press Esc to return.

• Add Page enum.
• Add vertical Menu page.
• Add navigation state.
• Add M to open menu.
• Add ↑/↓ selection.
• Add Enter to open selected page.
• Add Esc back.
• Add placeholder pages for Doctor/Tor/Network/Site/Settings/Diagnostics/Help.
• Keep Logs working if it already exists.
• Preserve current dashboard layout.