Add shared utilities and refactor iOS codebase for DRY compliance

Create centralized shared utilities in iosApp/Shared/:
- Extensions: ViewExtensions, DateExtensions, StringExtensions, DoubleExtensions
- Components: FormComponents, SharedEmptyStateView, ButtonStyles
- Modifiers: CardModifiers
- Utilities: ValidationHelpers, ErrorMessages

Migrate existing views to use shared utilities:
- LoginView: Use IconTextField, FieldLabel, FieldError, OrganicPrimaryButton
- TaskFormView: Use .loadingOverlay() modifier
- TaskCard/DynamicTaskCard: Use .toFormattedDate() extension
- CompletionCardView: Use .toCurrency() (with KotlinDouble support)
- ResidenceDetailView: Use OrganicEmptyState, StandardLoadingView
- Profile views: Use .standardFormStyle(), .sectionBackground()
- Form views: Use consistent form styling modifiers

Benefits:
- Eliminates ~180 lines of duplicate code
- Consistent styling across all forms and components
- KotlinDouble extensions for seamless KMM interop
- Single source of truth for UI patterns

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

iosApp/iosApp/Residence/ResidenceDetailView.swift

@@ -197,12 +197,7 @@ private extension ResidenceDetailView {
     }
     
     var loadingView: some View {
-        VStack(spacing: 16) {
-            ProgressView()
-            Text(L10n.Residences.loadingResidence)
-                .font(.subheadline)
-                .foregroundColor(Color.appTextSecondary)
-        }
+        StandardLoadingView(message: L10n.Residences.loadingResidence)
     }
     
     @ViewBuilder
@@ -282,43 +277,12 @@ private extension ResidenceDetailView {
                     .padding()
             } else if contractors.isEmpty {
                 // Empty state with organic styling
-                VStack(spacing: 16) {
-                    ZStack {
-                        Circle()
-                            .fill(
-                                RadialGradient(
-                                    colors: [
-                                        Color.appPrimary.opacity(0.12),
-                                        Color.appPrimary.opacity(0.04)
-                                    ],
-                                    center: .center,
-                                    startRadius: 0,
-                                    endRadius: 50
-                                )
-                            )
-                            .frame(width: 80, height: 80)
-
-                        Image(systemName: "person.crop.circle.badge.plus")
-                            .font(.system(size: 32, weight: .medium))
-                            .foregroundColor(Color.appPrimary.opacity(0.6))
-                    }
-
-                    VStack(spacing: 8) {
-                        Text(L10n.Residences.noContractors)
-                            .font(.system(size: 17, weight: .semibold, design: .rounded))
-                            .foregroundColor(Color.appTextPrimary)
-
-                        Text(L10n.Residences.addContractorsPrompt)
-                            .font(.system(size: 14, weight: .medium))
-                            .foregroundColor(Color.appTextSecondary)
-                            .multilineTextAlignment(.center)
-                    }
-                }
-                .frame(maxWidth: .infinity)
-                .padding(OrganicSpacing.spacious)
-                .background(OrganicCardBackground(showBlob: true, blobVariation: 1))
-                .clipShape(RoundedRectangle(cornerRadius: 28, style: .continuous))
-                .naturalShadow(.subtle)
+                OrganicEmptyState(
+                    icon: "person.crop.circle.badge.plus",
+                    title: L10n.Residences.noContractors,
+                    subtitle: L10n.Residences.addContractorsPrompt,
+                    blobVariation: 1
+                )
             } else {
                 // Contractors list
                 VStack(spacing: 12) {