Component selection shortcut (#1139)

This PR introduces a new keyboard shortcut to improve the efficiency of
selecting components in the app. Users can now quickly select components
using Meta + Shift + C for Mac and Ctrl + Shift + C for Other devices
(Windows/Linux)

    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Add a shortcut to quickly activate the component selector from the
preview. Use Meta+Shift+C on macOS and Ctrl+Shift+C on Windows/Linux.

- **New Features**
- Added useShortcut hook to handle key combos and prevent default on
match.
  - Wired shortcut in PreviewIframe with OS detection for Meta vs Ctrl.
- Forwarded keydown events from the iframe to the parent via postMessage
(dyad-shortcut-triggered) so the shortcut works inside preview content.

<!-- End of auto-generated description by cubic. -->

worker/dyad-component-selector-client.js

@@ -2,6 +2,9 @@
   const OVERLAY_ID = "__dyad_overlay__";
   let overlay, label;
 
+  //detect if the user is using Mac
+  const isMac = navigator.platform.toUpperCase().indexOf("MAC") >= 0;
+
   // The possible states are:
   // { type: 'inactive' }
   // { type: 'inspecting', element: ?HTMLElement }
@@ -146,6 +149,31 @@
     );
   }
 
+  function onKeyDown(e) {
+    // Ignore keystrokes if the user is typing in an input field, textarea, or editable element
+    if (
+      e.target.tagName === "INPUT" ||
+      e.target.tagName === "TEXTAREA" ||
+      e.target.isContentEditable
+    ) {
+      return;
+    }
+
+    // Forward shortcuts to parent window
+    const key = e.key.toLowerCase();
+    const hasShift = e.shiftKey;
+    const hasCtrlOrMeta = isMac ? e.metaKey : e.ctrlKey;
+    if (key === "c" && hasShift && hasCtrlOrMeta) {
+      e.preventDefault();
+      window.parent.postMessage(
+        {
+          type: "dyad-select-component-shortcut",
+        },
+        "*",
+      );
+    }
+  }
+
   /* ---------- activation / deactivation --------------------------------- */
   function activate() {
     if (state.type === "inactive") {
@@ -178,6 +206,9 @@
     if (e.data.type === "deactivate-dyad-component-selector") deactivate();
   });
 
+  // Always listen for keyboard shortcuts
+  window.addEventListener("keydown", onKeyDown, true);
+
   function initializeComponentSelector() {
     if (!document.body) {
       console.error(