fix(mail/delivery): Centralize runtime/plugin imports and switch modules to use plugins exports; unify EventEmitter usage; update Deno dependencies and small path/server refactors

ts/paths.ts

@@ -19,3 +19,9 @@ export const logsDir = plugins.path.join(configDir, 'logs');
 
 // DKIM keys directory
 export const dkimKeysDir = plugins.path.join(configDir, 'dkim-keys');
+
+// Keys directory (alias for compatibility)
+export const keysDir = dkimKeysDir;
+
+// DNS records directory
+export const dnsRecordsDir = plugins.path.join(configDir, 'dns-records');