fix(#338): Disable QuickCaptureWidget in production with Coming Soon

- Show Coming Soon placeholder in production for both widget versions
- Widget available in development mode only
- Added tests verifying environment-based behavior
- Use runtime check for testability (isDevelopment function vs constant)

Refs #338

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

apps/web/src/components/widgets/QuickCaptureWidget.tsx

@@ -1,12 +1,48 @@
 /**
  * Quick Capture Widget - idea/brain dump input
+ *
+ * In production, shows a Coming Soon placeholder since the feature
+ * is not yet complete. Full functionality available in development mode.
  */
 
 import { useState } from "react";
 import { Send, Lightbulb } from "lucide-react";
 import type { WidgetProps } from "@mosaic/shared";
 
-export function QuickCaptureWidget({ id: _id, config: _config }: WidgetProps): React.JSX.Element {
+/**
+ * Check if we're in development mode (runtime check for testability)
+ */
+function isDevelopment(): boolean {
+  return process.env.NODE_ENV === "development";
+}
+
+/**
+ * Compact Coming Soon placeholder for widget contexts
+ */
+function WidgetComingSoon(): React.JSX.Element {
+  return (
+    <div className="flex flex-col h-full items-center justify-center p-4 text-center">
+      {/* Lightbulb Icon */}
+      <Lightbulb className="w-8 h-8 text-gray-300 mb-3" aria-hidden="true" />
+
+      {/* Coming Soon Badge */}
+      <span className="inline-block px-3 py-1 bg-blue-100 text-blue-700 text-xs font-medium rounded-full mb-2">
+        Coming Soon
+      </span>
+
+      {/* Feature Name */}
+      <h3 className="text-sm font-medium text-gray-700 mb-1">Quick Capture</h3>
+
+      {/* Description */}
+      <p className="text-xs text-gray-500">Quickly jot down ideas for later organization.</p>
+    </div>
+  );
+}
+
+/**
+ * Internal Quick Capture Widget implementation
+ */
+function QuickCaptureWidgetInternal({ id: _id, config: _config }: WidgetProps): React.JSX.Element {
   const [input, setInput] = useState("");
   const [isSubmitting, setIsSubmitting] = useState(false);
   const [recentCaptures, setRecentCaptures] = useState<string[]>([]);
@@ -92,3 +128,19 @@ export function QuickCaptureWidget({ id: _id, config: _config }: WidgetProps): R
     </div>
   );
 }
+
+/**
+ * Quick Capture Widget
+ *
+ * In production: Shows Coming Soon placeholder
+ * In development: Full widget functionality
+ */
+export function QuickCaptureWidget(props: WidgetProps): React.JSX.Element {
+  // In production, show Coming Soon placeholder
+  if (!isDevelopment()) {
+    return <WidgetComingSoon />;
+  }
+
+  // In development, show full widget functionality
+  return <QuickCaptureWidgetInternal {...props} />;
+}