feat: 1.0.4 release

[insertish]

• [x] https://github.com/revoltchat/desktop/issues/82
• [x] https://github.com/revoltchat/desktop/issues/2
• [x] https://github.com/revoltchat/desktop/issues/8
• [x] https://github.com/revoltchat/desktop/issues/14
• [x] feat: add spell check
• [x] fix: correct icon bundling

After release is finalised, clean up and merge:

• [x] https://github.com/revoltchat/desktop/pull/57