feat: Announcements

[madkarmaa]

What's this?

This is a new, more updated continuation of #195

TODO:

• [x] Add styles
• [x] Add login admin functionality
• [x] Add 3 dots on cards for admins to edit or delete
• [ ] Add edit, add, delete announcement admin functionality
• [x] Remove boilerplate response code
• [ ] Footer shifts up when content is little
• [x] Add wrong credentials message
• [x] Attachments not shown on announcement page
• [x] Only first attachment shown on announcements page
• [x] New API changes need to be applied (such as paging or tags)
• [x] Some design suggestions should be applied:

[Ushie]

Only first attachment shown on announcements page

Well, that's intentional, as it's a thumbnail not a gallery

[oSumAtrIX]

The first attachment is not intended to be a thumbnail. There is no concept of thumbnails in announcements, so you arbitrarily chose the first as one. Can't say if this is really a good idea

[madkarmaa]