Add Edit and Delete Functionality for Activities

[rnavyaprabha]

This PR implements basic edit and delete functionality for activities (tickets) in the app. Users can now:
Edit the title, reference link, and time spent on an activity.
Delete an activity with a confirmation prompt.
Key changes:
Added edit and delete buttons to each activity card in the UI.
When editing, the activity form is pre-filled with the selected activity’s details.
Added server methods for updating and deleting activities, with permission checks.
UI updates reactively after editing or deleting an activity.

YouTube video explaining the functionality:
https://youtube.com/shorts/o-y0ju_SBhs?si=ZI1Qz_rUbs6OfOdF

Note:
When user edits the time admin will be notified about the change.
Advanced features like moving a pasted URL to the reference field and auto filling the title while editing will also be implemented in a separate PR.

[tbaugher-mie]

Please update the icons. Use something like font awesome or something, for example. https://fontawesome.com/search

[rnavyaprabha]

@tbaugher-mie @trip-flip Did the code changes, can you please review it now?

[tbaugher-mie]

https://youtube.com/shorts/_HqHBYELwx4

@rnavyaprabha Deleting tickets will delete them from the session. Tickets should not be removed from running or completed sessions; that is a deletion of history. For running sessions, deleted tickets should appear as if they are inactive, and with their time before deletion still visible. For completed sessions, they should just not be removed at all.

[tbaugher-mie]

Another thing, this seems like a conflict of features for the PR. We already have a PR for this, as you know. #31 This shouldn't be present here.