chore: revert breaking dependency changes

[susnux]

• revert @nextcloud/files to v3 (Nextcloud up to 33 as supported by stable6)
• revert vue tsconfig to ~0.5 for Vue 2

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 41.78%. Comparing base (1645d94) to head (2b3d66f).
⚠️ Report is 2 commits behind head on stable6.

Additional details and impacted files

@@           Coverage Diff            @@
##           stable6    #2515   +/-   ##
========================================
  Coverage    41.78%   41.78%           
========================================
  Files           16       16           
  Lines          414      414           
  Branches        79       79           
========================================
  Hits           173      173           
  Misses         215      215           
  Partials        26       26           

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