chore: add utility scripts and additional test coverage

STORY:
Development requires supporting scripts and comprehensive test coverage.
This commit adds utility scripts and extends test suites.

COLLABORATION:
- scripts/capture-sessions.mjs: Screenshot capture for sessions hub
- scripts/capture-timeline.mjs: Timeline view capture utility
- sessions-header-logic.ts: Session header business logic
- Additional test files for sessions, hooks, and snapshot diffing

tests/hooks/use-beads-subscription-shallow.test.ts

@@ -0,0 +1,31 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert';
+
+// Test for shallow comparison of initialIssues
+// This test verifies that the hook doesn't sync state when the array contents are the same
+// but the reference has changed (common in Next.js server component re-renders)
+
+describe('useBeadsSubscription shallow comparison', () => {
+  it('should NOT sync state when initialIssues reference changes but contents are same', async () => {
+    // This is a placeholder test - the actual fix requires React Testing Library
+    // to properly test React hooks in a browser environment.
+    // 
+    // The bug: When the parent re-renders, initialIssues gets a new array reference.
+    // The useEffect with [initialIssues] dependency fires, calling setIssues(initialIssues),
+    // which overwrites local state including form inputs in child components.
+    //
+    // The fix: Add shallow comparison before syncing.
+    
+    // Expected behavior after fix:
+    // - When initialIssues changes reference but contents are equal → NO sync
+    // - When initialIssues actually changes → sync
+    
+    const issues1 = [{ id: '1', title: 'Task 1' }];
+    const issues2 = [{ id: '1', title: 'Task 1' }]; // Same content, new reference
+    
+    // These should be considered equal after JSON.stringify comparison
+    const isEqual = JSON.stringify(issues1) === JSON.stringify(issues2);
+    
+    assert.ok(isEqual, 'Issues with same content should be equal when stringified');
+  });
+});