Add ellipsis menu to event page and add copy link

[nabramow]

• Adds our usual EllipsisMenu to the EventPage
• Add "copy link" as an item
• Move "Duplicate event", "cancel event" and "edit event" in there too
• Add back button to EditEventPage
• Swapped order of buttons in "Cancel event dialog" and made the "no" outlined to match other places

Part of #8367

Testing

Explain how you tested this PR and give clear steps so the reviewer can replicate.

• Click the items and make sure they work

Web frontend checklist

• There are no console warnings when running the app
• Added tests where relevant
• Clicked around my changes running locally and it works
• Checked Desktop, Mobile and Tablet screen sizes

For maintainers

• Maintainers can push commits to my branch
• Maintainers can merge this PR for me

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Project	Deployment	Actions	Updated (UTC)
couchers	Ready	Preview	May 10, 2026 10:57am

[jesseallhands]

This looks good, though I would like the "copy link" paperclip symbol to be a one-click button outside of a menu (otherwise it will be overlooked by a lot of people). But I do think we should keep the 3-dot menu for organizers since it's nice to group those other options there.

[github-actions]

📝 Release Notes

This PR should be included in the release notes.

Suggested release note:

Added a copy link option and streamlined event management actions on event pages to make sharing and editing events easier

🤖 Bot Debug Information

Model: couchers.openai.gpt-5.4
Decision: include
Reasoning: This is a small but user-visible UX improvement on event pages: it adds a copy link action and reorganizes event management actions into a clearer menu, plus a back button on edit event. While not a major feature, event sharing/copying is useful and noticeable to users.