📁 feat: Integrate SharePoint File Picker and Download Workflow (#8651)

* feat(sharepoint): integrate SharePoint file picker and download workflow
Introduces end‑to‑end SharePoint import support:
* Token exchange with Microsoft Graph and scope management (`useSharePointToken`)
* Re‑usable hooks: `useSharePointPicker`, `useSharePointDownload`,
  `useSharePointFileHandling`
* FileSearch dropdown now offers **From Local Machine** / **From SharePoint**
  sources and gracefully falls back when SharePoint is disabled
* Agent upload model, `AttachFileMenu`, and `DropdownPopup` extended for
  SharePoint files and sub‑menus
* Blurry overlay with progress indicator and `maxSelectionCount` limit during
  downloads
* Cache‑flush utility (`config/flush-cache.js`) supporting Redis & filesystem,
  with dry‑run and npm script
* Updated `SharePointIcon` (uses `currentColor`) and new i18n keys
* Bug fixes: placeholder syntax in progress message, picker event‑listener
  cleanup
* Misc style and performance optimizations

* Fix ESLint warnings

---------

Co-authored-by: Atef Bellaaj <slalom.bellaaj@external.daimlertruck.com>

packages/data-provider/src/api-endpoints.ts

@@ -305,3 +305,7 @@ export const verifyTwoFactorTemp = () => '/api/auth/2fa/verify-temp';
 export const memories = () => '/api/memories';
 export const memory = (key: string) => `${memories()}/${encodeURIComponent(key)}`;
 export const memoryPreferences = () => `${memories()}/preferences`;
+
+// SharePoint Graph API Token
+export const graphToken = (scopes: string) =>
+  `/api/auth/graph-token?scopes=${encodeURIComponent(scopes)}`;