fix(07): UAT fixes — SMTP test email, DKV routing, Exchange domain field

- SMTP: add test-to field, send real email via sendMail() instead of verify()
- SMTP: fix no_auth warning shown as error for open-relay servers
- DKV: register dkv-fleet in MODULE_REGISTRY (fixes "Modul nicht gefunden")
- DKV: add dynamic [category]/[moduleSlug]/settings + vehicles sub-routes
- DKV: settings/vehicles links use useParams for consistent URLs
- DKV: add gear icon settings link to module main page
- DKV: rename module to "DKV-Rechnung" in seed + translations
- DKV: add optional domain field for Exchange (WebCredentials 3rd arg)
- DKV: hide IMAP-only fields (Port/Verschlüsselung/Ordner) when Exchange selected
- DKV: hide Exchange-only field (Domain) when IMAP selected
- Prisma: add domain column to DkvModuleConfig

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/research/.cache/8eb4181e3441a3eee19f1dd1eb33e597cb3de673fcbe9ce1c10d0c5d388f444e.json

@@ -0,0 +1 @@
+{"content":"For Exchange calendar access: ews-javascript-api v0.15.3 (EWS/SOAP, last updated 2024-05) or @microsoft/microsoft-graph-client v3.0.7 (REST/Graph API, last updated 2023-09). MS Graph is the modern approach for Exchange Online/M365. EWS is needed for on-premises Exchange. Both support OAuth.","source":"web","provider":"websearch","confidence":"MEDIUM","fetched_at":"2026-06-23T12:25:14.344Z","ttl":86400000,"kind":"web"}