Add Docker Hub support with path and scope handling

Introduces Docker Hub-specific configuration and utilities, including path and scope transformation for library images. Updates the main logic to handle Docker Hub authentication and path rewriting. Adds tests for Docker Hub path, scope, and authentication header parsing. Updates documentation to reflect Docker Hub support and usage examples.

test/docker-hub.test.js

@@ -0,0 +1,95 @@
+import { describe, expect, it } from 'vitest';
+import {
+  DOCKER_HUB_REGISTRY,
+  isDockerHub,
+  parseDockerAuthenticate,
+  transformDockerHubPath,
+  transformDockerHubScope
+} from '../src/config/docker.js';
+
+describe('Docker Hub Support', () => {
+  describe('parseDockerAuthenticate', () => {
+    it('should parse Docker Hub WWW-Authenticate header correctly', () => {
+      const authenticateStr = 'Bearer realm="https://auth.docker.io/token",service="registry.docker.io"';
+      const result = parseDockerAuthenticate(authenticateStr);
+      
+      expect(result.realm).toBe('https://auth.docker.io/token');
+      expect(result.service).toBe('registry.docker.io');
+    });
+
+    it('should throw error for invalid WWW-Authenticate header', () => {
+      const invalidHeader = 'Bearer invalid-header';
+      
+      expect(() => parseDockerAuthenticate(invalidHeader)).toThrow('invalid Www-Authenticate Header');
+    });
+  });
+
+  describe('transformDockerHubPath', () => {
+    it('should add library prefix for Docker Hub library images', () => {
+      const path = '/v2/nginx/manifests/latest';
+      const result = transformDockerHubPath(path);
+      
+      expect(result).toBe('/v2/library/nginx/manifests/latest');
+    });
+
+    it('should add library prefix for blob requests', () => {
+      const path = '/v2/alpine/blobs/sha256:abc123';
+      const result = transformDockerHubPath(path);
+      
+      expect(result).toBe('/v2/library/alpine/blobs/sha256:abc123');
+    });
+
+    it('should not modify paths with existing namespace', () => {
+      const path = '/v2/nginxinc/nginx-unprivileged/manifests/latest';
+      const result = transformDockerHubPath(path);
+      
+      expect(result).toBe('/v2/nginxinc/nginx-unprivileged/manifests/latest');
+    });
+
+    it('should not modify non-Docker API paths', () => {
+      const path = '/some/other/path';
+      const result = transformDockerHubPath(path);
+      
+      expect(result).toBe('/some/other/path');
+    });
+  });
+
+  describe('transformDockerHubScope', () => {
+    it('should add library prefix to scope for library images', () => {
+      const scope = 'repository:nginx:pull';
+      const result = transformDockerHubScope(scope);
+      
+      expect(result).toBe('repository:library/nginx:pull');
+    });
+
+    it('should not modify scope with existing namespace', () => {
+      const scope = 'repository:nginxinc/nginx-unprivileged:pull';
+      const result = transformDockerHubScope(scope);
+      
+      expect(result).toBe('repository:nginxinc/nginx-unprivileged:pull');
+    });
+
+    it('should handle empty scope', () => {
+      const result = transformDockerHubScope('');
+      expect(result).toBe('');
+    });
+
+    it('should handle null scope', () => {
+      const result = transformDockerHubScope(null);
+      expect(result).toBe(null);
+    });
+  });
+
+  describe('isDockerHub', () => {
+    it('should identify Docker Hub registry URL', () => {
+      expect(isDockerHub(DOCKER_HUB_REGISTRY)).toBe(true);
+      expect(isDockerHub('https://registry-1.docker.io')).toBe(true);
+    });
+
+    it('should not identify other registries as Docker Hub', () => {
+      expect(isDockerHub('https://ghcr.io')).toBe(false);
+      expect(isDockerHub('https://quay.io')).toBe(false);
+      expect(isDockerHub('https://gcr.io')).toBe(false);
+    });
+  });
+});