Add auth service, storage service, types, and logging middleware

- Auth service: hashPassword/verifyPassword via bcrypt
- Storage service: saveFile, getFilePath, deleteStoredFile with ENOENT handling
- Types: JwtPayload interface
- Logging middleware: createLogger writing AUTH_FAILURE, AUTH_SUCCESS, FILE_NOT_FOUND
- 27 tests passing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/services/storage.ts

@@ -0,0 +1,21 @@
+import { writeFile, unlink } from 'fs/promises';
+import { join } from 'path';
+
+export async function saveFile(uploadDir: string, storedName: string, data: Buffer): Promise<string> {
+  await writeFile(join(uploadDir, storedName), data);
+  return storedName;
+}
+
+export function getFilePath(uploadDir: string, storedName: string): string {
+  return join(uploadDir, storedName);
+}
+
+export async function deleteStoredFile(uploadDir: string, storedName: string): Promise<void> {
+  try {
+    await unlink(join(uploadDir, storedName));
+  } catch (err: unknown) {
+    if ((err as NodeJS.ErrnoException).code !== 'ENOENT') {
+      throw err;
+    }
+  }
+}