Fix tap gesture blocked by line brush drag gesture

The DragGesture with minimumDistance: 0 for line brush mode was
consuming all touches, preventing tap detection for Object/Person/Wire
tools. Fixed by:

1. Only attaching line brush gesture when in line brush mode
2. Added conditional .if() view modifier extension
3. Added debug logging to tap gesture to track gesture flow

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

CheapRetouch/Features/Editor/CanvasView.swift

@@ -8,6 +8,19 @@
 import SwiftUI
 import UIKit
 
+// MARK: - Conditional View Modifier
+
+extension View {
+    @ViewBuilder
+    func `if`<Content: View>(_ condition: Bool, transform: (Self) -> Content) -> some View {
+        if condition {
+            transform(self)
+        } else {
+            self
+        }
+    }
+}
+
 struct CanvasView: View {
     @Bindable var viewModel: EditorViewModel
 
@@ -67,11 +80,14 @@ struct CanvasView: View {
                 }
             }
             .contentShape(Rectangle())
-            .gesture(lineBrushGesture(in: geometry))
             .gesture(tapGesture(in: geometry))
             .gesture(magnificationGesture(in: geometry))
             .simultaneousGesture(dragGesture(in: geometry))
             .simultaneousGesture(longPressGesture)
+            // Only attach line brush gesture when in line brush mode
+            .if(viewModel.selectedTool == .wire && viewModel.isLineBrushMode) { view in
+                view.gesture(lineBrushGesture(in: geometry))
+            }
             .onTapGesture(count: 2) {
                 doubleTapZoom()
             }
@@ -127,16 +143,30 @@ struct CanvasView: View {
     private func tapGesture(in geometry: GeometryProxy) -> some Gesture {
         SpatialTapGesture()
             .onEnded { value in
-                guard !viewModel.isProcessing,
-                      !viewModel.showingMaskConfirmation,
-                      viewModel.selectedTool != .brush else { return }
+                DebugLogger.action("CanvasView tap at \(value.location)")
+                DebugLogger.state("isProcessing: \(viewModel.isProcessing), showingMaskConfirmation: \(viewModel.showingMaskConfirmation), tool: \(viewModel.selectedTool)")
+
+                guard !viewModel.isProcessing else {
+                    DebugLogger.log("Tap ignored - isProcessing")
+                    return
+                }
+                guard !viewModel.showingMaskConfirmation else {
+                    DebugLogger.log("Tap ignored - showingMaskConfirmation")
+                    return
+                }
+                guard viewModel.selectedTool != .brush else {
+                    DebugLogger.log("Tap ignored - brush tool selected")
+                    return
+                }
 
                 // Skip tap if in line brush mode
                 if viewModel.selectedTool == .wire && viewModel.isLineBrushMode {
+                    DebugLogger.log("Tap ignored - line brush mode")
                     return
                 }
 
                 let imagePoint = convertViewPointToImagePoint(value.location, in: geometry.size)
+                DebugLogger.log("Converted to image point: \(imagePoint)")
                 Task {
                     await viewModel.handleTap(at: imagePoint)
                 }
@@ -146,9 +176,11 @@ struct CanvasView: View {
     private func lineBrushGesture(in geometry: GeometryProxy) -> some Gesture {
         DragGesture(minimumDistance: 0)
             .onChanged { value in
+                // Only activate for wire tool in line brush mode
                 guard viewModel.selectedTool == .wire,
-                      viewModel.isLineBrushMode,
-                      !viewModel.isProcessing,
+                      viewModel.isLineBrushMode else { return }
+
+                guard !viewModel.isProcessing,
                       !viewModel.showingMaskConfirmation else { return }
 
                 let imagePoint = convertViewPointToImagePoint(value.location, in: geometry.size)