feat(files): use direct-to-storage upload for email and AI-chat attachments (#22610)

## Context

Follow-up to the direct-to-storage upload work (#22449 / #22531 / #22533
/ #22576). That migrated files-field, attachments and workflow uploads
off the buffered path. This PR does the same for the **last two
user-facing upload surfaces**: email attachments and AI-chat files.

## What this does

- Adds `EmailAttachment` and `AgentChat` to the server's
`DIRECT_UPLOAD_FILE_FOLDERS` allowlist. Both folders already resolve
through the workspace-custom-application path in
`resolveUploadLocation`, so no other server change is needed.
- Routes the two frontend hooks through the existing
`useDirectFileUpload` handshake (`createFileUpload` → `PUT` →
`completeFileUpload`):
- `useUploadEmailAttachment` → `FileFolder.EmailAttachment` (keeps its
existing `MAX_ATTACHMENT_SIZE` client check — email has a real send-size
limit).
  - `useAiChatFileUpload` → `FileFolder.AgentChat`.

Each hook keeps its public signature and return shape, so call sites are
unchanged. No schema change and no codegen needed — the
`CreateFileUpload`/`CompleteFileUpload` documents and the `FileFolder`
enum values already exist in `generated-metadata` from #22576.

## Why these are safe to migrate

Both server services (`file-ai-chat`, `file-email-attachment`) just
`writeFile` (store) and return a signed URL — no synchronous processing
of the bytes at upload time — so the store-and-reference direct-upload
flow fits exactly, same as files-field/workflow.

## Out of scope

`CorePicture` (avatars, member/workspace pictures, logos) stays on the
buffered path on purpose: small images that go through server-side image
handling and are served inline, where the 10 MB body limit is already
appropriate.

## Tests

Extends the `FileUploadService` unit spec with an `it.each` asserting
`createFileUpload` supports the `EmailAttachment` and `AgentChat`
folders.

## Verification

`typecheck` and `lint:diff-with-main` green on both `twenty-front` and
`twenty-server`. (The server jest suite couldn't run in my local sandbox
due to an unrelated config-import quirk present on a clean `main`
checkout too — CI runs it normally.)

https://claude.ai/code/session_015UH8KWmsB9zdYaog8MFG1d

---
_Generated by [Claude
Code](https://claude.ai/code/session_015UH8KWmsB9zdYaog8MFG1d)_

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packages/twenty-server/src/engine/core-modules/file/file-upload/services/file-upload.service.spec.ts

@@ -189,6 +189,30 @@ describe('FileUploadService', () => {
       );
       expect(result.contentType).toBe('application/octet-stream');
     });
+
+    it.each([FileFolder.EmailAttachment, FileFolder.AgentChat])(
+      'should support direct upload for the %s folder',
+      async (fileFolder) => {
+        fileStorageService.getPresignedUploadUrl.mockResolvedValueOnce(
+          'https://bucket/presigned-put',
+        );
+
+        const result = await service.createFileUpload({
+          workspaceId: 'workspace-id',
+          filename: 'document.pdf',
+          size: 1024,
+          fileFolder,
+        });
+
+        expect(fileStorageService.createPendingFile).toHaveBeenCalledWith(
+          expect.objectContaining({
+            fileFolder,
+            resourcePath: 'mocked-file-id.pdf',
+          }),
+        );
+        expect(result.uploadUrl).toBe('https://bucket/presigned-put');
+      },
+    );
   });
 
   describe('completeFileUpload', () => {

packages/twenty-server/src/engine/core-modules/file/file-upload/services/file-upload.service.ts

@@ -41,6 +41,8 @@ import { readReadablePrefix } from 'src/utils/read-readable-prefix';
 export const DIRECT_UPLOAD_FILE_FOLDERS = [
   FileFolder.FilesField,
   FileFolder.Workflow,
+  FileFolder.EmailAttachment,
+  FileFolder.AgentChat,
 ] as const;
 
 @Injectable()