fix(web): 修復 webpack build 錯誤 — 重複 flexShrink + firing_count undefined

header.tsx: 移除重複的 flexShrink: 0 屬性 (TS1117)
classic/page.tsx: firing_count ?? 0 處理 undefined (TS2322)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/components/layout/header.tsx

@@ -75,7 +75,6 @@ export function Header({
         background: '#faf9f3',
         overflow: 'hidden',
         transition: 'width 0.3s ease',
-        flexShrink: 0,
       }}>
         {/* NemoClaw mini SVG */}
         <div style={{ width: 36, height: 36, flexShrink: 0 }}>