iPad: more keyboard shortcuts, a New-chat button, and hover polish

Round out the Mac-parity keyboard/pointer affordances on the iPad split view.

Keyboard shortcuts (hidden buttons in SplitRootView carry them):
- ⌘N — start a new chat: select Home and focus the composer (also defaults the
  project). A one-shot Bool binding threads Home→StartChatComposer and is
  consumed on use, so it grabs focus on ⌘N but never on a later Home appearance
  (handles both "already on Home" via onChange and "switched from a session"
  via onAppear).
- ⌘1–4 — jump to Home / Projects / To-dos / Settings.
- ⌘R — refresh sessions.
- ⌘. — interrupt a running session (Mac's "stop"; otherwise only in the ⋯ menu).

UI:
- A visible "New chat" (compose) button in the sidebar toolbar runs the same
  action, so touch users get the affordance too (gated on control scope).

Hover (pointer):
- .hoverEffect on the transcript tool-call / tool-block rows and the Home
  in-progress session rows (native List rows already hover).

Verified in the iPad simulator: the New-chat action scrolls to + focuses the
composer with the project defaulted. Builds clean.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

NucleicRemote/NucleicRemote/Views/Composer.swift

@@ -5,11 +5,16 @@ import NucleicProtocol
 /// composer). Picks a project, types a prompt, optionally toggles Auto.
 struct StartChatComposer: View {
     @EnvironmentObject var store: RemoteStore
+    /// A one-shot request from the iPad `Cmd+N` shortcut to focus the prompt so a keyboard user can
+    /// start typing a new chat immediately. Consumed (reset to false) once handled, so it never
+    /// steals focus on a later Home appearance. `.constant(false)` for the iPhone/compact path.
+    var focusNewChat: Binding<Bool> = .constant(false)
     @State private var projectID: ProjectID?
     @State private var draft = ""
     @State private var auto = false
     @State private var model: String?
     @State private var effort = MobileEfforts.fallback
+    @FocusState private var draftFocused: Bool
     // Advanced options (the Mac new-session sheet's base branch + worktree fields).
     @State private var showOptions = false
     @State private var baseBranch = ""
@@ -79,6 +84,7 @@ struct StartChatComposer: View {
                     .lineLimit(1...5)
                     .orchestraGlow(active: MobileEfforts.isOrchestra(effort) && controlled)
                     .keyboardDismissable()
+                    .focused($draftFocused)
                 Button {
                     if let project = selected {
                         let branch = baseBranch.trimmingCharacters(in: .whitespaces)
@@ -107,6 +113,18 @@ struct StartChatComposer: View {
                 effort = levels.last ?? MobileEfforts.fallback
             }
         }
+        // A Cmd+N (iPad) focuses the prompt so the keyboard user can type a new chat immediately.
+        // onAppear handles the case where Cmd+N switched to Home from a session (composer just
+        // mounted); onChange handles Cmd+N while Home is already on screen. Consumed either way.
+        .onAppear { consumeFocusRequest() }
+        .onChange(of: focusNewChat.wrappedValue) { consumeFocusRequest() }
+    }
+
+    private func consumeFocusRequest() {
+        guard focusNewChat.wrappedValue else { return }
+        if projectID == nil { projectID = store.dashboard.projects.first?.id }
+        draftFocused = true
+        focusNewChat.wrappedValue = false
     }
 }