Merge branch 'main' into embedded-vnc

# Conflicts:
#	client/ui/frontend/src/app.tsx
#	client/ui/frontend/src/modules/main/MainConnectionStatusSwitch.tsx
#	client/ui/i18n/locales/uk/common.json
#	go.sum

docs/custom-domain-validation.md

@@ -0,0 +1,28 @@
+A new custom domain name is converted to lowercase ASCII (punycode), with a
+trailing dot removed, before availability and DNS validation checks. Invalid
+names and wildcard registrations are rejected before storage.
+
+A custom domain registration must complete validation within 48 hours of
+creation. Retrying validation does not extend this window. Once validation
+succeeds, the registration is exempt from this expiration policy.
+
+Management removes expired, unvalidated registrations at startup and every
+60 minutes. While management is running, removal normally occurs between
+48 and 49 hours after registration. Validation is refused after the 48-hour
+deadline even if cleanup has not yet removed the registration.
+
+Removal releases the name for a new registration. The new registration must
+complete its own validation. Its account does not inherit validation or
+services from the expired registration.
+
+The original account receives a system activity event named
+`CustomDomainValidationExpired`, displayed as "Unvalidated domain registration
+expired". The event includes the domain name, original registration ID, and
+validation deadline.
+
+On upgrade, existing unvalidated registrations receive a 48-hour validation
+window. Restarting management does not extend a previously assigned deadline.
+
+Registrations with existing services, including services using subdomains, are
+retained for operator review. Management logs their account and domain IDs so
+an operator can identify and resolve those dependencies before cleanup.