feat: add 410 error handling, progress messages, touch targets, and tests (refs #145)

- Handle poll errors including 410 Gone in useManualExtraction hook
- Add specific progress stage messages (Preparing/Processing/Mapping/Complete)
- Enforce 44px minimum touch targets on all interactive elements
- Add tests for inline editing, mobile fullscreen, and desktop modal layouts

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

frontend/src/features/documents/components/DocumentForm.tsx

@@ -622,7 +622,12 @@ export const DocumentForm: React.FC<DocumentFormProps> = ({
                   sx={{ borderRadius: 1 }}
                 />
                 <div className="text-xs text-slate-500 dark:text-titanio mt-1">
-                  {extraction.progress > 0 ? `${extraction.progress}% complete` : 'Starting extraction...'}
+                  {extraction.progress >= 100 ? '100% - Complete' :
+                   extraction.progress >= 95 ? `${extraction.progress}% - Mapping maintenance schedules...` :
+                   extraction.progress >= 50 ? `${extraction.progress}% - Processing maintenance data...` :
+                   extraction.progress >= 10 ? `${extraction.progress}% - Preparing document...` :
+                   extraction.progress > 0 ? `${extraction.progress}% complete` :
+                   'Starting extraction...'}
                 </div>
               </div>
             </div>