Just-in-place widget: show code in search, show "source" and "current vs proposed" translations in edit

[farfalk]

Thank you for you work!

As per title:

• the string code in search would be a big helper when you need to precisely identify a string
• the source language translation would work like a "ground truth" and would also help search and identify the correct string;
• the current vs proposed (or: previous edit vs current edit) visualisation would be a QoL improvement during long edits session, as it would help you remember what you edited and how