feat(server): add global encryption module (AES-256-GCM) (#2400)

Provides an injectable EncryptionService that encrypts/decrypts strings
with AES-256-GCM using a key derived from APP_SECRET with domain
separation.

apps/server/src/integrations/encryption/encryption.errors.ts

@@ -0,0 +1,13 @@
+export class UnableToInitialize extends Error {
+  constructor(message: string) {
+    super(`Unable to initialize the encryption service: ${message}`);
+    this.name = 'UnableToInitialize';
+  }
+}
+
+export class UnableToDecrypt extends Error {
+  constructor(reason: string) {
+    super(`Unable to decrypt the ciphertext: ${reason}`);
+    this.name = 'UnableToDecrypt';
+  }
+}