feat(core): the e-mail server after Java, measured against Java

SMTP on port 25 stores mails for the domain's accounts as Java reads
them anew and tells a local sender of unknown recipients; POP3 on port
110 hands them out. The mailboxes are in the snapshot and go back into
the project. EmailRun plays four stories over the network; MailCases
feeds Java's workers without one (26 cases, de and en). 18 cases name
Java bugs that the core does not take.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/test/programLines.ts

@@ -2,7 +2,7 @@
 // message bundle says them: for comparing the core's structured lines with
 // what the Java oracle recorded (echoJava.test.ts, webJava.test.ts).
 
-import type { EchoServerLogEntry, SendFailure, SimpleClientLogEntry, WebBrowserLogEntry } from '../src/index.js';
+import type { EchoServerLogEntry, EmailServerLogEntry, PageLanguage, SendFailure, SimpleClientLogEntry, WebBrowserLogEntry } from '../src/index.js';
 
 /** Java's client and server look every 100 ms whether they are connected, or switched off; the core at once. */
 export const POLL_MILLISECONDS = 100;
@@ -88,3 +88,19 @@ export function browserText(entry: WebBrowserLogEntry): string | undefined {
     }
   }
 }
+
+/** The e-mail server's line as Java's window shows it (sw_smtpmitarbeiter_msg12 to msg14 in both languages). */
+export function emailServerText(entry: EmailServerLogEntry, language: PageLanguage = 'de'): string {
+  switch (entry.kind) {
+    case 'connectionOpened':
+      return '----';
+    case 'received':
+      return `${entry.address}< ${entry.text}`;
+    case 'sent':
+      return `${entry.address}> ${entry.text}`;
+    case 'sendFailed':
+      return language === 'de' ? `Fehler beim Senden an ${entry.address}` : `Error while sending ${entry.address}`;
+    case 'stored':
+      return language === 'de' ? `E-Mail für ${entry.username} im Postfach gespeichert.` : `E-mail for ${entry.username} saved in mailbox.`;
+  }
+}