chore: prepare 2.0.0-beta.17

[skjnldsv]

Version bump and changelog for 2.0.0-beta.17:

• the viewer's own Download, Delete and shortcuts outside Files (fix(viewer): offer Download and Delete, and the shortcuts, wherever the viewer is opened #95);
• the dark palette kept to the viewer's own parts, and the 'default' theme following the user's theme again (fix(viewer): keep the dark palette to the viewer's own parts #125);
• the encrypted media fetch (fix(media): fetch a file by hand from its own URL #98);
• vue and @nextcloud/vue moved to dependencies (fix(deps): make vue a dependency #121).

#122 and #123 were tooling only.

Text's port (nextcloud/text#9235) waits on #125 for its print tests.

👾 This pull request was assisted by Claude Code, commits carry an Assisted-by trailer.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.33%. Comparing base (a7f2467) to head (47359cb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #126   +/-   ##
=======================================
  Coverage   91.33%   91.33%           
=======================================
  Files          41       41           
  Lines        3532     3532           
  Branches      816      816           
=======================================
  Hits         3226     3226           
  Misses        287      287           
  Partials       19       19           

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