📁 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>

package.json

@@ -73,7 +73,8 @@
     "b:test:api": "cd api && bun run b:test",
     "b:balance": "bun config/add-balance.js",
     "b:list-balances": "bun config/list-balances.js",
-    "reset-terms": "node config/reset-terms.js"
+    "reset-terms": "node config/reset-terms.js",
+    "flush-cache": "node config/flush-cache.js"
   },
   "repository": {
     "type": "git",