Add "prefer SMTP" toggle to skip Microsoft Graph for email

When the M365 connector is connected the app always tries Graph first,
and a Graph 202 ends the send — so report mail to recipients Exchange
silently drops (Google-hosted subdomains of the O365 domain) never
reaches them, even with working SMTP configured.

New prefer_smtp flag gates all three Graph branches (smtp_test,
send_report, _maybe_send_auto_email) so they go straight to SMTP. UI
toggle #st-smtpPreferSmtp in Settings → E-mailrapport, saved/loaded by
scheduler.js, with da/de/en strings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lang/da.json

@@ -366,6 +366,7 @@
   "m365_smtp_recipients_hint": "Adskil med komma eller semikolon",
   "m365_smtp_save": "Gem",
   "m365_smtp_auto_email_manual": "Send rapport efter manuel scanning",
+  "m365_smtp_prefer_smtp": "Send altid via SMTP (spring Microsoft Graph over)",
   "m365_smtp_send": "Send nu",
   "m365_smtp_saved": "Indstillinger gemt.",
   "m365_smtp_sending": "Sender…",

lang/de.json

@@ -366,6 +366,7 @@
   "m365_smtp_recipients_hint": "Komma- oder semikolongetrennt",
   "m365_smtp_save": "Speichern",
   "m365_smtp_auto_email_manual": "Bericht nach manueller Suche senden",
+  "m365_smtp_prefer_smtp": "Immer via SMTP senden (Microsoft Graph überspringen)",
   "m365_smtp_send": "Jetzt senden",
   "m365_smtp_saved": "Einstellungen gespeichert.",
   "m365_smtp_sending": "Senden…",

lang/en.json

@@ -366,6 +366,7 @@
   "m365_smtp_recipients_hint": "Comma or semicolon separated",
   "m365_smtp_save": "Save",
   "m365_smtp_auto_email_manual": "Email report after manual scan",
+  "m365_smtp_prefer_smtp": "Always send via SMTP (skip Microsoft Graph)",
   "m365_smtp_send": "Send now",
   "m365_smtp_saved": "Settings saved.",
   "m365_smtp_sending": "Sending…",