Show running version and release updates in V2 Admin Settings

[Paul Lizer (paullizer)]

Summary

• V2 Admin Settings already received the running version but did not display it or check for releases. Show the server version and link to GitHub Releases when a strictly newer version is available.
• Share classic's server-side release checker and 24-hour cache across both admin interfaces. Preserve numeric release-tag selection and the three-second timeout; no manual refresh button or automatic upgrades.
• Report unavailable or stale checks without blocking settings editing. Failed attempts are cached when storage is available, and availability is always recomputed against the running version.
• Keep release metadata outside editable settings and retain existing admin authorization and secret redaction.

Linked issue

N/A. The user chose not to create a tracking issue.

Release Notes & Latest Features

• New Feature
• Bug Fix
• UI Enhancement
• Breaking Change
• Internal only

Is this visible to end users?

• Yes
• No

Is this admin-facing (Admin Settings, governance, deployment, config)?

• Yes
• No

Should this become a Latest Feature card?

• Yes
• No
• Already added

Screenshot needed for the card?

• Yes
• No
• Attached

Release notes were left unchanged because approval to update them was not received.

Version bump

• application/single_app/config.py VERSION third segment bumped, or not needed because this is docs-only
• deployers/version.txt bumped, or not needed because deployers/ was not changed

Application version: 0.261.125 -> 0.261.126. No deployer changes.

Testing / validation

• npm --prefix application/v2_ui run build passed.
• Targeted pytest run covering version status, settings schema, secret redaction, and live shell refresh: 42 passed plus 25 subtests; one known pre-existing schema test was excluded after confirming its failure. This includes 11 browser scenarios and 11 release-check functional tests.
• All three functional_tests/route_tests/ policy scripts passed under Python 3.12.
• test_docs_app_surface_coverage.py, test_docs_site_quality.py, and git diff --check passed. Generated surface inventory remains current.

Known unrelated failure: test_v2_admin_settings_schema.py::test_defaults_match_their_field_type reports that the existing m365_trusted_download_hosts textarea has a list default. Its implementation was unchanged by this PR.

Browser coverage uses the built SPA with intercepted APIs plus the classic version markup. Backend tests mock HTTP/storage boundaries; no live GitHub release request or real settings write is required.

Documentation

• Release notes updated, or not needed
• Feature documentation updated, or not needed
• Fix documentation updated, or not needed

Updated the administration guide, added V2_ADMIN_VERSION_STATUS_FIX.md, cross-referenced the earlier update-banner fix, and documented [APP_UPDATES]. Release notes remain deferred as noted above.

Security checklist

• New Flask routes include @swagger_route(security=get_auth_security())
• Settings sent to non-admin frontends use sanitize_settings_for_user()
• Browser JavaScript is served from local SimpleChat static assets only; no CDN-hosted JS
• No secrets, keys, connection strings, or local-only artifacts are included

No new routes or non-admin settings payloads were added. Existing admin route guards and secret redaction are preserved; GitHub is contacted server-side.