Improve Quick Actions sheet styling to match platform conventions

- Replace custom ZStack header with NavigationStack + navigationTitle +
  xmark toolbar button, matching the pattern used by other sheets
- Remove divider between tab bar and content (was sandwiching input bar)
- Add sheet design guidelines to CLAUDE.md covering form vs utility sheet
  patterns, transparent background pitfalls, and divider usage

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

Author: mcintyre94

CLAUDE.md

@@ -119,6 +119,17 @@ The app runs on iPhone, iPad, and Mac (Designed for iPad). Keep all three in min
 - Run `mkdir -p /home/sprite/project` on first chat message if no project dir exists
 - Settings captions: when a setting needs an explanation, wrap the control and caption text together in a `VStack(alignment: .leading, spacing: 8)` inside the `Section`, with the caption styled `.font(.subheadline).foregroundStyle(.secondary)`.
 
+### Sheet design
+
+Two sheet patterns in use — match the right one:
+
+- **Form sheets** (data entry, e.g. New Sprite, New Checkpoint): `NavigationStack` > `Form` > `.navigationTitle` + `.navigationBarTitleDisplayMode(.inline)` + `.toolbar` with text Cancel / action-name buttons (e.g. "Cancel" / "Create"). Keep text labels — they're more informative than icons for actions with consequences.
+- **Utility/panel sheets** (e.g. Quick Actions): `NavigationStack` > custom content > `.navigationTitle` + `.navigationBarTitleDisplayMode(.inline)` + `Image(systemName: "xmark")` in `.cancellationAction`. `TabView` is fine for tabs here. Note: if you ever need a transparent sheet background, `TabView` will block it — its UIKit-backed view hierarchy ignores SwiftUI `.background(.clear)` and would need replacing with a custom VStack + HStack tab bar.
+
+Both sheet types use opaque `Color(.systemBackground)` throughout — do **not** use material/transparent backgrounds on sheets. Materials suit bars and floating elements (popovers, context menus), not sheets.
+
+Avoid sandwiching a fixed element (e.g. input bar) between two `Divider`s. A divider above the input bar separating scrollable content from a fixed action area is standard; a second one below it is redundant.
+
 ## Testing
 
 - Run unit tests after making changes to verify nothing is broken

Wisp/Views/QuickActions/BashQuickView.swift

@@ -51,6 +51,7 @@ struct BashQuickView: View {
                     }
                     .frame(maxWidth: .infinity, minHeight: 100, alignment: .topLeading)
                 }
+                .background(.clear)
                 .defaultScrollAnchor(.bottom)
                 .onChange(of: viewModel.output) {
                     proxy.scrollTo("output", anchor: .bottom)

Wisp/Views/QuickActions/QuickActionsView.swift

@@ -10,27 +10,20 @@ struct QuickActionsView: View {
     @State private var selectedTab = 0
 
     var body: some View {
-        VStack(spacing: 0) {
-            headerBar
-            Divider()
+        NavigationStack {
             tabs
+                .navigationTitle(selectedTab == 0 ? "Quick Chat" : "Bash")
+                .navigationBarTitleDisplayMode(.inline)
+                .toolbar {
+                    ToolbarItem(placement: .cancellationAction) {
+                        Button(action: handleDone) {
+                            Image(systemName: "xmark")
+                        }
+                    }
+                }
         }
     }
 
-    private var headerBar: some View {
-        ZStack(alignment: .center) {
-            Text(selectedTab == 0 ? "Quick Chat" : "Bash")
-                .font(.headline)
-            HStack {
-                Button("Done", action: handleDone)
-                    .padding(.leading)
-                Spacer()
-            }
-        }
-        .frame(height: 44)
-        .background(.bar)
-    }
-
     private var tabs: some View {
         TabView(selection: $selectedTab) {
             QuickChatView(viewModel: viewModel.quickChatViewModel)

Wisp/Views/QuickActions/QuickChatView.swift

@@ -41,6 +41,7 @@ struct QuickChatView: View {
                     }
                     .frame(maxWidth: .infinity, alignment: .leading)
                 }
+                .background(.clear)
                 .defaultScrollAnchor(.bottom)
                 .onChange(of: viewModel.response) {
                     proxy.scrollTo("response", anchor: .bottom)