MAESTRO: Add sendToAgent keyboard shortcut handler for context transfer

- Add setSendToAgentModalOpen to keyboard handler context in App.tsx
- Add sendToAgent shortcut handler (Cmd+Shift+A) in useMainKeyboardHandler.ts
- Handler checks for supportsContextMerge capability before opening modal

src/renderer/App.tsx

@@ -6516,8 +6516,9 @@ export default function MaestroConsole() {
     handleSidebarNavigation, handleTabNavigation, handleEnterToActivate, handleEscapeInMain,
     // Agent capabilities
     hasActiveSessionCapability,
-    // Merge session modal
-    setMergeSessionModalOpen
+    // Merge session modal and send to agent modal
+    setMergeSessionModalOpen,
+    setSendToAgentModalOpen
   };
 
   // Update flat file list when active session's tree, expanded folders, filter, or hidden files setting changes

src/renderer/hooks/useMainKeyboardHandler.ts

@@ -291,6 +291,13 @@ export function useMainKeyboardHandler(): UseMainKeyboardHandlerReturn {
           ctx.setMergeSessionModalOpen(true);
         }
       }
+      else if (ctx.isShortcut(e, 'sendToAgent')) {
+        e.preventDefault();
+        // Only show send to agent modal if agent supports context merge
+        if (ctx.hasActiveSessionCapability('supportsContextMerge') && ctx.activeSession?.activeTabId) {
+          ctx.setSendToAgentModalOpen(true);
+        }
+      }
       else if (ctx.isShortcut(e, 'systemLogs')) {
         e.preventDefault();
         ctx.setLogViewerOpen(true);