- Search now hits the backend (debounced) so results aren't truncated to the
first loaded page: /received gains a `q` filter (sender/subject); the frontend
passes the debounced term to every list query. The instant client-side filter
stays for responsiveness.
- Reply/compose recipient extracts the bare address from a "Name <addr>" From
header (extractEmail) — also used for the customer-lookup key.
- Added the full de + en `messages.*` and `email.customerMailbox.*` translation
namespaces (were English inline-fallbacks only). Swiss-German spelling.