VSN-26857 feat(reports): add inspection mobile signing flow and real-time status sync

This MR adds changes to allow drivers to sign reports directly from the app, with real-time status updates.

Signing from mobile (reportDetailScreen)

• "Signer le rapport" button displayed when driverSigned === false
• Tapping the button: requests geolocation (non-blocking if denied), saves
  location to backend, fetches an embedded DocuSign signing URL, and opens
  it via WebBrowser.openAuthSessionAsync with deep link
  vsndriverfront://signing-complete for automatic browser dismissal
• hasSigned state: button is hidden immediately upon returning from the
  browser (before the API refresh completes)
• Screen auto-refreshes on focus via useFocusEffect — status updates
  automatically when navigating back from the browser or any other screen

Status synchronization (vehicleInspectionService.ts)

• ReportResponseDto extended with signatureStatus, driverSigned,
• mapStatus prioritizes signatureStatus when present, covering all
  signature states: PENDING_SIGNATURE, DRIVER_SIGNED, COMPANY_SIGNED, COMPLETED, DECLINED, FAILED
• New API methods: getDriverSigningUrl, saveSignatureLocation

Status labels & colors (vehicleInspection.ts)

• ReportStatus type extended with all signature states
• GENERATED and PENDING_SIGNATURE unified under "En attente de signature"
• DRIVER_SIGNED / COMPANY_SIGNED
• COMPLETED: "Terminé"

Inspection detail (inspectionDetailScreen)

• "Modifier" button hidden when inspection is in signing state
  (PENDING_SIGNATURE) to prevent edits during an active signature process