Add centralized DateUtils and enhance contractor detail views

- Add DateUtils.kt for shared Kotlin date formatting with formatDate,
  formatDateMedium, formatDateTime, formatRelativeDate, and isOverdue
- Add DateUtils.swift for iOS with matching date formatting functions
- Enhance ContractorDetailScreen (Android) with quick action buttons
  (call, email, website, directions), clickable contact rows, residence
  association, statistics section, and metadata
- Enhance ContractorDetailView (iOS) with same features, refactored into
  smaller @ViewBuilder functions to fix Swift compiler type-check timeout
- Fix empty string handling in iOS - check !isEmpty in addition to != nil
  for optional fields like phone, email, website, address
- Update various task and document views to use centralized DateUtils

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

iosApp/iosApp/Subviews/Task/CompletionCardView.swift

@@ -8,7 +8,7 @@ struct CompletionCardView: View {
     var body: some View {
         VStack(alignment: .leading, spacing: 8) {
             HStack {
-                Text(formatDate(completion.completionDate))
+                Text(DateUtils.formatDateMedium(completion.completionDate))
                     .font(.caption)
                     .fontWeight(.semibold)
                     .foregroundColor(Color.appPrimary)
@@ -99,21 +99,4 @@ struct CompletionCardView: View {
             PhotoViewerSheet(images: completion.images)
         }
     }
-
-    private func formatDate(_ dateString: String) -> String {
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
-        if let date = formatter.date(from: dateString) {
-            formatter.dateStyle = .medium
-            formatter.timeStyle = .none
-            return formatter.string(from: date)
-        }
-        // Try without time
-        formatter.dateFormat = "yyyy-MM-dd"
-        if let date = formatter.date(from: dateString) {
-            formatter.dateStyle = .medium
-            return formatter.string(from: date)
-        }
-        return dateString
-    }
 }