fix(history): wait for the Files router before tagging its entries

[skjnldsv]

nextcloud/server#63954 fails "closing resets history so back does not re-open a file" since the Files app moved to vue-router 5 (nextcloud/server#61291). goToRoute() now lands the navigation asynchronously and resolves once the new entry exists, but pushToHistory() tagged the entry with its viewerPos right after asking for the push, so it tagged the previous entry. Closing then read an offset of 0, skipped the history.go(-offset), and back landed on an entry with openfile=true.

Every history change now waits for the router's navigation, queued behind the ones before it. goToRoute's type says it may return a promise, which the Files router has always done.

A new test has the router create its entry only after a delay, like vue-router 5: it fails on main with expected undefined to be 1 and passes here. The existing history tests wait for the queue. Not run against a real server here, the server PR's e2e will tell.

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

[codecov]

Codecov Report

❌ Patch coverage is 92.10526% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.94%. Comparing base (babd3d0) to head (de10b9b).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/utils/history.ts	92.10%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #74      +/-   ##
==========================================
+ Coverage   88.90%   88.94%   +0.03%     
==========================================
  Files          39       39              
  Lines        2776     2786      +10     
  Branches      574      576       +2     
==========================================
+ Hits         2468     2478      +10     
  Misses        301      301              
  Partials        7        7              

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