fix: Fix regression issue with drag-drop in editor

[cguedes]

The upload files feature broke the drag-drop of draggable elements in the TipTap editor!

• We've had to deactivate Tauri's fileDropEnabled
• Implement drag-and-drop with custom HTML events (only for PDF files)
• Hover effect when drag-drop for user feedback
• This PR adds initial UI for the application footer with ingestion status
• This PR also adds a new app menu entry References -> Upload... to open the upload files dialog

refstudio-pr-192.mov

NOTE: This PR don't aim to improve the left references sidebar.

This will close #173

[codecov]

Codecov Report

Merging #192 (8fa98c4) into main (30cd1b5) will increase coverage by 3.44%.
The diff coverage is 88.96%.

@@            Coverage Diff             @@
##             main     #192      +/-   ##
==========================================
+ Coverage   66.91%   70.36%   +3.44%     
==========================================
  Files          87       91       +4     
  Lines        4498     4592      +94     
  Branches      331      370      +39     
==========================================
+ Hits         3010     3231     +221     
+ Misses       1471     1344     -127     
  Partials       17       17              

Impacted Files	Coverage Δ
src/App.tsx	0.00% <0.00%> (ø)
src/filesystem.ts	17.98% <0.00%> (-0.49%)	⬇️
src/events.ts	80.00% <80.00%> (+2.72%)	⬆️
src/panels/references/ReferencesPanel.tsx	97.26% <95.45%> (+12.01%)	⬆️
src/panels/references/FilesDragDropZone.tsx	98.33% <98.33%> (ø)
src/components/footer/Footer.tsx	100.00% <100.00%> (ø)
src/components/footer/FooterItem.tsx	100.00% <100.00%> (ø)
src/hooks/useAsyncEffect.ts	100.00% <100.00%> (ø)
src/hooks/useListenEvent.ts	100.00% <100.00%> (ø)
src/panels/references/ReferencesDropZone.tsx	100.00% <100.00%> (+100.00%)	⬆️
... and 2 more

... and 1 file with indirect coverage changes

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[sehyod]

Looks good! I let two comments, but nothing blocking.
While testing locally, I realised that you can still drag and drop a file on the title bar and it opens it with no way of getting out. It's very specific, I don't think it has to be fixed in this PR, but we should create a ticket for it to fix it later on.