Split reviewer more menu actions

[andrewsanchez]

Source split from ankitects#4289.

Breakdown sections covered:

• 14. More menu
• 15. Flag menu and toggling
• 16. Mark note
• 17. Bury / suspend
• 18. More-menu actions
• 20. Page tooltips

Source fidelity:

• This PR copies exact final file contents from PR Feat/Svelte port for reviewer ankitects/anki#4289.
• No implementation changes were made while splitting.
• Commit author is preserved as Luc Mcgrady.

Follow-up notes from the breakdown:

• The menu may eventually be replaced by the shared ContextMenu work.
• Overflow, hover-open parity, and menu-dismiss behavior were called out for follow-up.
• Tooltip handling is split between page tooltips and Qt undo notifications.