feat: add encryption and date service utilities

- Implemented EncryptionService for secure data handling with AES encryption.
- Created DateService for advanced date manipulation and formatting.
- Developed EncryptionDemo and DateServiceComponent for interactive demonstrations.
- Added LocalStorage demo for encrypted data storage and retrieval.
- Established ESLint and TypeScript configurations for utils package.
- Included example utility function for demonstration purposes.

packages/utils/src/encryption/encryption-key.ts

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+export const ENC_STORAGE_KEY = 'zkwqyo3RpNEh8un2CIAs'; //TODO change value from environment

packages/utils/src/encryption/index.ts

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+import { AES, enc } from 'crypto-js';
+import { ENC_STORAGE_KEY } from './encryption-key';
+
+/**
+ * Interface contract supaya method konsisten
+ */
+interface IEncryptionService {
+  encrypt(data: string): string;
+  decrypt(encryptedData: string): string;
+}
+
+export class EncryptionService implements IEncryptionService {
+  private readonly _key: string;
+
+  /**
+   * @param key (Optional) Jika tidak diisi, otomatis pakai ENC_STORAGE_KEY
+   */
+  constructor(key: string = ENC_STORAGE_KEY) {
+    if (!key) {
+      throw new Error('[EncryptionService] Encryption key is missing/empty.');
+    }
+    this._key = key;
+  }
+
+  /**
+   * Mengenkripsi string plain text.
+   */
+  public encrypt(data: string): string {
+    if (!data) {
+      return '';
+    }
+    return AES.encrypt(data, this._key).toString();
+  }
+
+  /**
+   * Mendekripsi string terenkripsi.
+   * Mengembalikan string kosong '' jika gagal decrypt atau format salah.
+   */
+  public decrypt(encryptedData: string): string {
+    if (!encryptedData) {
+      return '';
+    }
+
+    try {
+      const bytes = AES.decrypt(encryptedData, this._key);
+      const originalText = bytes.toString(enc.Utf8);
+
+      // Validasi tambahan: jika hasil decrypt kosong, berarti key salah atau data corrupt
+      if (!originalText) {
+        return '';
+      }
+
+      return originalText;
+    } catch (error) {
+      console.error('[EncryptionService] Decryption failed:', error);
+      return '';
+    }
+  }
+
+  // --- Static Helper (Singleton Pattern sederhana) ---
+  // Supaya tidak perlu 'new EncryptionService()' berulang kali
+  private static instance: EncryptionService;
+
+  public static getInstance(): EncryptionService {
+    if (!EncryptionService.instance) {
+      EncryptionService.instance = new EncryptionService();
+    }
+    return EncryptionService.instance;
+  }
+}