feat(backups): Daily Raven digest of sites whose backups keep failing

[regdocs]

Adds a daily Raven alert, posted to the server alerts channel, listing every site that hit the daily failed backup limit in the last 24h.

This is the same limit (max_failed_backup_attempts_in_a_day, default 6) that already emails the team. Right now only the customer finds out when a site's backups keep failing. With this, we see it too, in one message a day instead of one per site.

Message

Sites With All Backup Attempts Failed - 2

Sites with 6 or more failed backups in the last 24h

Site	Server	Plan	Team Email	Failed Backups	Last Successful Backup
site-a.example.com	f1-example	$25/mo	owner-a@example.com	9	2026-09-20 03:10
site-b.example.com	f2-example	Dedicated	owner-b@example.com	6	Never

• Each site name links to that site's failed backups in desk.
• Rows are sorted by number of failures, most first.
• At most 50 sites are shown, and anything beyond that goes into a "... N more sites" row.
• If no site hit the limit, no message is sent.

Changes

• server_monitoring.py: adds alert_on_sites_with_all_backup_attempts_failed(), which runs on the daily scheduler.
• site_backup.py: moves the limit lookup into get_max_failed_backup_attempts(), so the email check and the digest share it.
• Adds tests in test_server_monitoring.py.

🤖 Generated with Claude Code

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Adds daily alert for sites with repeated backup failures.

The PR appears safe to merge; the missing overflow test is non-blocking.

_{Reviews (1) · Last reviewed commit: "feat(backups): Daily Raven digest of sit..."}

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.38554% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.04%. Comparing base (079059d) to head (dce25a7).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
press/press/doctype/server/server_monitoring.py	93.54%	2 Missing ⚠️
press/press/doctype/site_backup/site_backup.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           develop    #7577       +/-   ##
============================================
- Coverage    86.75%   63.04%   -23.71%     
============================================
  Files          157     1082      +925     
  Lines        29602   105450    +75848     
  Branches      1976     1977        +1     
============================================
+ Hits         25681    66485    +40804     
- Misses        3864    38908    +35044     
  Partials        57       57               

Flag	Coverage Δ
dashboard	86.76% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mergify]

Tick the box to add this pull request to the merge queue (same as @mergifyio queue).

• Queue this pull request