[PER-10773] Add banner alerting users of expected downtime on the 15th Oct

[aasandei-vsp]

Manual test cases — October 15th downtime banner

The visible change: from October 12th at 3pm Central, a banner across the top of the app reads The Permanent.org platform will be temporarily unavailable on October 15th, 2026 from approximately 3-5pm Central Time while we perform routine maintenance. Thank you for your patience..

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Before the notice window

Scenario — nothing shows yet

1. Set the clock to October 12th, 2026, 2:55 PM, open a private window and sign in.
   • EXPECTED: No banner anywhere.

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Inside the notice window ⭐

Scenario — the banner appears on every surface

1. Set the clock to October 12th, 2026, 3:05 PM, open a private window and go to the sign-in page.
   • EXPECTED: The banner shows at the top with the exact copy above.
2. Sign in and open My Files.
   • EXPECTED: The banner shows, and the left sidebar starts below it rather than underneath it.
3. Open the public archive link.
   • EXPECTED: The banner shows.
4. Open the share link.
   • EXPECTED: The banner shows.

Scenario — still there during the downtime

1. Set the clock to October 15th, 2026, 4:55 PM, open a private window and sign in.
   • EXPECTED: The banner still shows.

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Dismissing ⭐

Scenario — a dismissal sticks

1. Set the clock to October 13th, 2026, 10:00 AM. In a normal (not private) window, sign in.
2. Click the close icon on the banner.
   • EXPECTED: The banner disappears and the left sidebar moves back up.
3. Reload the page.
   • EXPECTED: The banner stays hidden.

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After the downtime

Scenario — the banner goes away on its own

1. Set the clock to October 15th, 2026, 5:01 PM, open a private window and sign in.
   • EXPECTED: No banner.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.66%. Comparing base (05374e1) to head (c672020).
⚠️ Report is 30 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1201      +/-   ##
==========================================
+ Coverage   53.64%   53.66%   +0.02%     
==========================================
  Files         368      368              
  Lines       12925    12925              
  Branches     2363     2363              
==========================================
+ Hits         6933     6936       +3     
+ Misses       5753     5749       -4     
- Partials      239      240       +1     

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