Update v0.1.26 changelogs with UI text fix

Added the Settings Maintenance page text update to the official
v0.1.26 release notes before the first build.

Changes:
- Updated docs/changelog.md with User Interface subsection
- Updated changelog.py with User Interface subsection
- Both now document the test email text change (3→1, Veeam only)

All three changelogs (changelog.md, changelog.py, changelog-claude.md)
now include this UI improvement in v0.1.26.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

containers/backupchecks/src/backend/app/changelog.py

@@ -34,6 +34,14 @@ CHANGELOG = [
                             "Reduced test email generation from 3 emails per status to 1 email per status for simpler testing",
                             "Each button now creates exactly 1 test mail instead of 3"
                         ]
+                    },
+                    {
+                        "subtitle": "User Interface",
+                        "changes": [
+                            "Updated Settings → Maintenance page text for test email generation to match actual behavior",
+                            "Changed description from '3 emails simulating Veeam, Synology, and NAKIVO' to '1 Veeam Backup Job email'",
+                            "Updated button labels from '(3)' to '(1)' on all test email generation buttons"
+                        ]
                     }
                 ]
             }

docs/changelog.md

@@ -50,6 +50,11 @@ This critical bug fix release resolves ticket system display issues where resolv
 - Reduced test email generation from 3 emails per status to 1 email per status
 - Each button now creates exactly 1 test mail instead of 3 for simpler testing
 
+**User Interface:**
+- Updated Settings → Maintenance page text for test email generation
+- Changed description from "3 emails simulating Veeam, Synology, and NAKIVO" to "1 Veeam Backup Job email"
+- Updated button labels from "(3)" to "(1)" to match actual behavior
+
 *Result:*
 - ✅ Resolved tickets stop appearing immediately after resolution
 - ✅ Consistent behavior across all pages (Job Details, Run Checks, Run Checks popup)