refactor(capture): memoize writable lists in the capture bar

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/capture/InstantCaptureBar.tsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useRef, useState } from 'react';
+import React, { useEffect, useRef, useState, useMemo } from 'react';
 import {
   Mic,
   MicOff,
@@ -38,7 +38,8 @@ export const InstantCaptureBar: React.FC<InstantCaptureBarProps> = ({
   hideTargetPicker = false,
   fixedTarget,
 }) => {
-  const writableLists = lists.filter((l) => l.isOwner || l.role !== 'viewer');
+  // Read-only shared lists cannot take new items; stable reference for the effect below
+  const writableLists = useMemo(() => lists.filter((l) => l.isOwner || l.role !== 'viewer'), [lists]);
   const [content, setContent] = useState('');
   const [priority, setPriority] = useState<PriorityLevel>('normal');
   const [dueDate, setDueDate] = useState('');