26.8.20260804

• SECURITY: this release fixes multiple high level security vulnerabilities, everyone is strongly adviced to update to it!
• Admin: really fix lost background image, if config from apps like calendar or addressbook is saved
• CalDAV/Calendar: fix EX/RDATE were exported wrong (timezone shifted) for server-timezones NOT UTC
• Customfields: fix multiline text and richtext CFs collapsing to almost nothing in Firefox
• Invoices: export exemption reason (code) to XML and automatic fill it for category-code "AE" with "Reverse charge" and "VATEX-EU-AE"
• OpenID: bump to current upstream (league v9, steverhoades v3, Slim 4, lcobucci/jwt 5)
• OpenIDConnect/Authentication: fix inverted email_verified check and config key mismatch
• Status/Jitsi: tolerate legacy too-short secrets, validate new ones in admin config
• WebAuthN: former EPL app allowing to use WebAuthN as 2nd factor either with passkeys, platform authenticators (e.g. Windows Hello) or hardware tokens like Yubikeys