🪣 fix: S3 path-style URL support for MinIO, R2, and custom endpoints (#11894)

* 🪣 fix: S3 path-style URL support for MinIO, R2, and custom endpoints

`extractKeyFromS3Url` now uses `AWS_BUCKET_NAME` to automatically detect and
strip the bucket prefix from path-style URLs, fixing `NoSuchKey` errors on URL
refresh for any S3-compatible provider using a custom endpoint (MinIO, Cloudflare
R2, Hetzner, Backblaze B2, etc.). No additional configuration required — the
bucket name is already a required env var for S3 to function.

`initializeS3` now passes `forcePathStyle: true` to the S3Client constructor
when `AWS_FORCE_PATH_STYLE=true` is set. Required for providers whose SSL
certificates do not support virtual-hosted-style bucket subdomains (e.g. Hetzner
Object Storage), which previously caused 401 / SignatureDoesNotMatch on upload.

Additional fixes:
- Suppress error log noise in `extractKeyFromS3Url` catch path: plain S3 keys
  no longer log as errors, only inputs that start with http(s):// do
- Fix test env var ordering so module-level constants pick up `AWS_BUCKET_NAME`
  and `S3_URL_EXPIRY_SECONDS` correctly before the module is required
- Add missing `deleteRagFile` mock and assertion in `deleteFileFromS3` tests
- Add `AWS_BUCKET_NAME` cleanup to `afterEach` to prevent cross-test pollution
- Add `initializeS3` unit tests covering endpoint, forcePathStyle, credentials,
  singleton, and IRSA code paths
- Document `AWS_FORCE_PATH_STYLE` in `.env.example`, `dotenv.mdx`, and `s3.mdx`

* 🪣 fix: Enhance S3 URL key extraction for custom endpoints

Updated `extractKeyFromS3Url` to support precise key extraction when using custom endpoints with path-style URLs. The logic now accounts for the `AWS_ENDPOINT_URL` and `AWS_FORCE_PATH_STYLE` environment variables, ensuring correct key handling for various S3-compatible providers.

Added unit tests to verify the new functionality, including scenarios for endpoints with base paths. This improves compatibility and reduces potential errors when interacting with S3-like services.

api/test/services/Files/S3/crud.test.js

@@ -19,6 +19,7 @@ jest.mock('@aws-sdk/client-s3');
 jest.mock('@librechat/api', () => ({
   initializeS3: jest.fn(),
   deleteRagFile: jest.fn().mockResolvedValue(undefined),
+  isEnabled: jest.fn((val) => val === 'true'),
 }));
 
 jest.mock('@librechat/data-schemas', () => ({
@@ -841,5 +842,35 @@ describe('S3 CRUD Operations', () => {
         ),
       ).toBe('images/user123/avatar.png');
     });
+
+    it('should use endpoint base path when AWS_ENDPOINT_URL and AWS_FORCE_PATH_STYLE are set', () => {
+      process.env.AWS_BUCKET_NAME = 'test-bucket';
+      process.env.AWS_ENDPOINT_URL = 'https://minio.example.com';
+      process.env.AWS_FORCE_PATH_STYLE = 'true';
+      jest.resetModules();
+      const { extractKeyFromS3Url: fn } = require('~/server/services/Files/S3/crud');
+
+      expect(fn('https://minio.example.com/test-bucket/images/user123/file.jpg')).toBe(
+        'images/user123/file.jpg',
+      );
+
+      delete process.env.AWS_ENDPOINT_URL;
+      delete process.env.AWS_FORCE_PATH_STYLE;
+    });
+
+    it('should handle endpoint with a base path', () => {
+      process.env.AWS_BUCKET_NAME = 'test-bucket';
+      process.env.AWS_ENDPOINT_URL = 'https://example.com/storage/';
+      process.env.AWS_FORCE_PATH_STYLE = 'true';
+      jest.resetModules();
+      const { extractKeyFromS3Url: fn } = require('~/server/services/Files/S3/crud');
+
+      expect(fn('https://example.com/storage/test-bucket/images/user123/file.jpg')).toBe(
+        'images/user123/file.jpg',
+      );
+
+      delete process.env.AWS_ENDPOINT_URL;
+      delete process.env.AWS_FORCE_PATH_STYLE;
+    });
   });
 });