feat(mobile): add pre-login legal pages, multi-image selection, file detail view, search, i18n, HEIC support

- Add Privacy Policy, Terms of Service, and Imprint links to WelcomeScreen
  and LoginScreen for GDPR/Apple compliance (pre-login access)
- Enable multiple image selection in photo library picker
- Add HEIC/HEIF image support to backend (allowed_types, convert_to_pdf, upload handler)
- Create FileDetailScreen with processing status and logs
- Add search bar to FilesScreen with debounced search
- Set up i18n with expo-localization (EN, DE, ES, FR, IT)
- Add language selector to ProfileScreen settings
- Add Imprint link to ProfileScreen legal section
- Update docs and tests

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

mobile/src/services/api.ts

@@ -78,6 +78,32 @@ export interface UploadResponse {
   };
 }
 
+export interface ProcessingLog {
+  id: number;
+  task_id: string;
+  step_name: string;
+  status: string;
+  message: string;
+  timestamp: string;
+}
+
+export interface FileDetail {
+  file: {
+    id: number;
+    filehash: string;
+    original_filename: string;
+    local_filename: string;
+    file_size: number;
+    mime_type: string;
+    created_at: string;
+  };
+  processing_status: ProcessingStatus;
+  logs: ProcessingLog[];
+  files_on_disk: {
+    original: boolean;
+  };
+}
+
 // ---------------------------------------------------------------------------
 // Base API client
 // ---------------------------------------------------------------------------
@@ -229,6 +255,11 @@ class DocuElevateAPI {
     );
     return data.processing_status;
   }
+
+  /** Get full file details including processing logs. */
+  async getFileDetail(fileId: number): Promise<FileDetail> {
+    return this.request<FileDetail>("GET", `/api/files/${fileId}`);
+  }
 }
 
 export const api = new DocuElevateAPI();