feat(PROJ-2): EML/MBOX-Upload für alle Benutzer zugänglich

- Backend: neue Routen POST /api/upload + GET /api/upload/{jobID}/progress (nur Auth, kein Admin)
- api.ts: uploadMailFilesUser + getUploadProgressUser für /api/upload
- search/page.tsx: Importieren-Button + Upload-Dialog mit Drag-and-Drop, Fortschrittsanzeige und automatischer Suchlisten-Aktualisierung nach Import

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/api.ts

@@ -484,3 +484,22 @@ export async function uploadMailFiles(files: File[]): Promise<{ job_id: string }
 export async function getUploadProgress(jobID: string): Promise<UploadJob> {
   return request<UploadJob>(`/api/admin/upload/${jobID}/progress`);
 }
+
+export async function uploadMailFilesUser(files: File[]): Promise<{ job_id: string }> {
+  const form = new FormData();
+  for (const f of files) form.append("files", f);
+  const res = await fetch(`${API_BASE}/api/upload`, {
+    method: "POST",
+    credentials: "include",
+    body: form,
+  });
+  if (!res.ok) {
+    const body = await res.text();
+    throw new Error(body || `Upload failed: ${res.status}`);
+  }
+  return res.json();
+}
+
+export async function getUploadProgressUser(jobID: string): Promise<UploadJob> {
+  return request<UploadJob>(`/api/upload/${jobID}/progress`);
+}