feat(fls): import the e-mail programs into the editor model

The e-mail client and server of every host come into the model (core:
EmailClientConfiguration, EmailServerConfiguration, EmailMessage), from
Java's view:

- the server's accounts are those of /mailserver/konten.txt, as Java reads
  them at every simulation start; without the file those of the bean list,
  which Java would drop;
- the client's account is that of /konten.txt; without it the first of an
  older file's kontoListe, which FILIUS 2.14 no longer reads;
- messages are numbered per program in folder order, as Swift does; the
  sent folder's are sent; a date is taken only when the file gives one.

Departures from Swift: accounts and messages stay where Swift drops what
fails its checks; first and last name stay apart; a port that is no number
is the default, with a warning. On the corpus the model matches Swift's on
all 13 files; the one Swift error is named (it numbers a mailbox's messages
as their received time and writes that into the konten.txt it rewrites).

The Swift dump now carries the e-mail state, and the file system
comparison leaves out only Swift's hidden state files (and the directories
it makes for them) instead of all of /mail, /mailserver and /peer2peer.

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

packages/fls/src/importProject.ts

@@ -33,10 +33,10 @@
 //  - a web server's files stay in /webserver (its document root), where Swift
 //    moves them to /www; and no program state is written into a host's files
 //    (Swift keeps Gnutella and e-mail state there as hidden JSON files).
+//  - e-mail: see importEmail.ts;
 //  - a DNS server's records are what Java's server answers from /dns/hosts
 //    (see dnsHosts.ts); Swift reads the file its own way — tabs, comments,
 //    "IN", names with a leading digit — and drops Java's duplicates.
-// Not here yet: e-mail accounts.
 
 import {
   canonicalMacAddress,
@@ -65,6 +65,8 @@ import {
   type DhcpClientConfiguration,
   type DhcpServerConfiguration,
   type DnsServerConfiguration,
+  type EmailClientConfiguration,
+  type EmailServerConfiguration,
   type EchoServerConfiguration,
   type GnutellaConfiguration,
   type InstallableProgram,
@@ -92,6 +94,7 @@ import {
   type VirtualFileContent,
 } from '@mdg-filius/core';
 import { dnsRecordsOf, javaHostsFileContent, readDnsHosts } from './dnsHosts.js';
+import { emailClientConfiguration, emailServerConfiguration } from './importEmail.js';
 import type { FlsApplicationClass, FlsFileTree, FlsFirewall } from './systemSoftware.js';
 import type { FlsDocumentationItem, FlsInterface, FlsNode, FlsNodeClass, FlsTopology } from './topology.js';
 
@@ -119,6 +122,8 @@ export interface ImportedProject {
   webServerConfigurations: Map<Id, WebServerConfiguration>;
   gnutellaConfigurations: Map<Id, GnutellaConfiguration>;
   dnsServerConfigurations: Map<Id, DnsServerConfiguration>;
+  emailClientConfigurations: Map<Id, EmailClientConfiguration>;
+  emailServerConfigurations: Map<Id, EmailServerConfiguration>;
   echoServerConfigurations: Map<Id, EchoServerConfiguration>;
   simpleClientConfigurations: Map<Id, SimpleClientConfiguration>;
   /** In render order: rectangles below text, then by order. */
@@ -162,6 +167,8 @@ export function importProject(topology: FlsTopology, newId: () => Id): ImportedP
     webServerConfigurations: new Map(),
     gnutellaConfigurations: new Map(),
     dnsServerConfigurations: new Map(),
+    emailClientConfigurations: new Map(),
+    emailServerConfigurations: new Map(),
     echoServerConfigurations: new Map(),
     simpleClientConfigurations: new Map(),
   };
@@ -369,6 +376,8 @@ type SystemConfigurations = Pick<
   | 'webServerConfigurations'
   | 'gnutellaConfigurations'
   | 'dnsServerConfigurations'
+  | 'emailClientConfigurations'
+  | 'emailServerConfigurations'
   | 'echoServerConfigurations'
   | 'simpleClientConfigurations'
 >;
@@ -393,6 +402,10 @@ export const PROGRAM_OF_CLASS: Readonly<Record<FlsApplicationClass, InstallableP
 /** The web server's document root: where Java keeps its files. */
 export const JAVA_WEB_ROOT = '/webserver';
 
+function warnAt(node: TopologyNode, warnings: string[]): (message: string) => void {
+  return (message) => warnings.push(`node '${node.displayName}': ${message}`);
+}
+
 /** The program parts of Swift's finalizeCurrentNodeCandidate, for a PC or notebook. */
 function registerPrograms(source: FlsNode, node: TopologyNode, system: SystemConfigurations, warnings: string[]): void {
   const installed = new Set<InstallableProgram>();
@@ -420,9 +433,7 @@ function registerPrograms(source: FlsNode, node: TopologyNode, system: SystemCon
         const primary = trimmedOrEmpty(source.interfaces[0]?.ip);
         const forwarding = recursive && forwarder !== '' && forwarder !== primary;
         const hosts = javaHostsFileContent(source.system.fileSystem);
-        const records = dnsRecordsOf(readDnsHosts(hosts ?? ''), (message) =>
-          warnings.push(`node '${node.displayName}': ${message}`),
-        );
+        const records = dnsRecordsOf(readDnsHosts(hosts ?? ''), warnAt(node, warnings));
         system.dnsServerConfigurations.set(
           node.id,
           forwarding
@@ -431,6 +442,12 @@ function registerPrograms(source: FlsNode, node: TopologyNode, system: SystemCon
         );
         break;
       }
+      case 'emailClient':
+        system.emailClientConfigurations.set(node.id, emailClientConfiguration(application, warnAt(node, warnings)));
+        break;
+      case 'emailServer':
+        system.emailServerConfigurations.set(node.id, emailServerConfiguration(application, warnAt(node, warnings)));
+        break;
       case 'firewall':
         if (application.firewall !== undefined) {
           system.firewallConfigurationsByNodeId.set(node.id, firewallConfigurationOf(application.firewall, `node '${node.displayName}'`, warnings));