App startup should not fail when enhanced citations storage is unreachable

[paullizer]

Summary

When enhanced citations are enabled, the latest application version can fail to start if it cannot reach the configured storage account. Startup should not be blocked by enhanced citations storage connectivity; the application should still run as long as Cosmos DB connectivity is available.

Background

A customer upgraded from an older version around 0.222.229 to the latest 0.250.x+ version. Enhanced citations were already enabled, but storage account access was not functional. The upgrade introduced a startup path that now attempts to access the storage account early enough that the application does not run at all when that storage access fails.

Current behavior

• Enhanced citations are enabled.
• The configured storage account is unreachable, inaccessible, or misconfigured.
• Application startup fails and the app does not run.
• Admins may not have a clear application-level indication that enhanced citations storage connectivity is the cause.

Expected behavior

• Cosmos DB connectivity should be the only required dependency for the application to boot.
• Enhanced citations storage failures should be handled as a degraded optional capability, not as a fatal startup error.
• The application should inform admins that enhanced citations storage access is failing or misconfigured.
• Features that require enhanced citations storage should fail gracefully with a clear admin-facing error or health/status indication.

Acceptance criteria

• Application startup succeeds when Cosmos DB is reachable, even if enhanced citations storage is unreachable.
• Enhanced citations storage connectivity failures are logged and surfaced to admins without preventing startup.
• Enhanced citations behavior is disabled, degraded, or error-reported only where that feature is used.
• Startup and/or configuration validation avoids fatal storage account calls for enhanced citations.
• Regression coverage verifies startup with enhanced citations enabled and storage unavailable.

Notes

This should prevent optional storage connectivity issues from turning into full application outages during upgrades or configuration drift.

[paullizer]

Implementation update for #1155:

• Changed Enhanced Citations startup initialization so it builds the Blob service client without live storage container exists() or create_container() calls.
• Added non-secret runtime startup status and an Admin Settings connection test so admins can explicitly validate Enhanced Citations storage reachability/container access.
• Moved Enhanced Citations container readiness to the upload path, where missing containers are created on demand when permissions allow it.
• Added fix documentation, release notes, functional regression coverage, and UI contract coverage under version 0.250.126.

Validation completed:

• python functional_tests\test_enhanced_citations_startup_storage_degradation.py
• python -m pytest ui_tests\test_admin_enhanced_citations_storage_status.py -q
• python -m py_compile application\single_app\config.py application\single_app\functions_documents.py application\single_app\route_backend_settings.py application\single_app\route_frontend_admin_settings.py functional_tests\test_enhanced_citations_startup_storage_degradation.py ui_tests\test_admin_enhanced_citations_storage_status.py
• node --check application\single_app\static\js\admin\admin_settings.js
• git -c core.whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol diff --check

Next step: commit, push, and open the PR.