feat(admin): add Provider column to Login-Übersicht

The audit log records *how* each login happened in the action name
(`auth.login.passkey`, `auth.bearer.success`, …) but the table
collapsed all of that into a single Aktion label. Admins now see
the credential type as a separate column with a lucide glyph
(KeyRound / Fingerprint / Cpu / Globe) so password-vs-passkey-vs-API
token attempts are distinguishable at a glance — and the column
maps cleanly into the CSV export.

The mapping itself (`providerForAction`) lives in `_shared.tsx`
alongside `useAuthActionLabels` so any later audit-feed consumer
picks up the same i18n + icon contract; a regression test pins
every action → provider edge and every provider → icon edge.

messages/de.json

@@ -1921,6 +1921,12 @@
     "ip": "IP",
     "location": "Standort",
     "timestamp": "Zeitpunkt",
+    "provider": "Anbieter",
+    "providerPassword": "Passwort",
+    "providerPasskey": "Passkey",
+    "providerApiToken": "API-Token",
+    "providerWithings": "Withings",
+    "providerUnknown": "Unbekannt",
     "dangerZone": "Gefahrenzone",
     "deleteAllData": "Alle Daten global löschen",
     "deleteAllDescription": "Löscht alle Mess-, Medikamenten-, Integrations- und Protokoll-Daten aller Benutzer. Benutzerkonten bleiben bestehen.",

messages/en.json

@@ -1921,6 +1921,12 @@
     "ip": "IP",
     "location": "Location",
     "timestamp": "Time",
+    "provider": "Provider",
+    "providerPassword": "Password",
+    "providerPasskey": "Passkey",
+    "providerApiToken": "API token",
+    "providerWithings": "Withings",
+    "providerUnknown": "Unknown",
     "dangerZone": "Danger Zone",
     "deleteAllData": "Delete all data globally",
     "deleteAllDescription": "Deletes all measurement, medication, integration, and log data for all users. User accounts will be preserved.",