Add CSV export for the activity/audit log page

[Lakes41]

Difficulty: Intermediate
Type: feature

Background
The /activity route displays an activity/audit log sourced from mock data, useful for admins reviewing guild/member actions.

Problem
Admins have no way to export the current (filtered) activity log for reporting or compliance purposes outside the app.

Expected outcome
An "Export CSV" button on the Activity page downloads the currently visible (filtered) log entries as a well-formed CSV file.

Suggested implementation

• Add a utility function that converts an array of activity-log entries into CSV text (handle comma/quote escaping).
• Trigger a client-side download via a Blob + temporary anchor element.
• Ensure the export respects any active filters/search on the page rather than exporting the full unfiltered dataset.

Acceptance criteria

• CSV includes header row matching displayed columns
• Special characters (commas, quotes, newlines) in log entries are properly escaped
• Export respects current filters
• Works in latest Chrome and Firefox

Likely affected files/directories

• apps/dashboard/app/activity/
• apps/dashboard/lib/ (new csv-export utility)

[Leyrioh7]

Hello Maintainer,

I'm genuinely interested in solving this issue, I have handled similar issues in the past and this shouldn't be a challenge

[grantfox-oss]

🦊 GrantFox — @Leyrioh7 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #290)
2. Your PR will be reviewed by the Adamantine-guild maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@Leyrioh7's PR #310 was approved and merged by @Lakes41.

🏆 @Leyrioh7: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (118 total points). Track your full progress on GrantFox.

👏 Great work, @Leyrioh7! Keep contributing to Adamantine-guild.