Implement foundational vault data models, service, and shared UI components.

src/app/models/csv-export.visitor.ts

@@ -0,0 +1,33 @@
+import { Account } from './account.model';
+import { AccountVisitor } from './visitor.interface';
+
+export class CsvExportVisitor implements AccountVisitor {
+  private rows: string[] = [];
+
+  constructor() {
+    // Add CSV header
+    this.rows.push('Service,Login,Password,Notes,UpdatedAt');
+  }
+
+  visitAccount(account: Account): void {
+    const data = account.decryptedData || {};
+    const service = this.escapeCsv(account.serviceName);
+    const login = this.escapeCsv(data['login'] || '');
+    const password = this.escapeCsv(data['password'] || '');
+    const notes = this.escapeCsv(data['notes'] || '');
+    const updatedAt = account.updatedAt.toISOString();
+
+    this.rows.push(`${service},${login},${password},${notes},${updatedAt}`);
+  }
+
+  getCsv(): string {
+    return this.rows.join('\n');
+  }
+
+  private escapeCsv(value: string): string {
+    if (value.includes(',') || value.includes('"') || value.includes('\n')) {
+      return `"${value.replace(/"/g, '""')}"`;
+    }
+    return value;
+  }
+}