feat(front): unify all front user pages to DESIGN.md brand #5B5FED; fix decimal-rgba off-brand purples missed by hex normalization (MarketPage focus shadow, LoginPage radial glow)

frontend/src/pages/front/WechatHistory.tsx

@@ -74,7 +74,7 @@ const WechatHistory: React.FC = () => {
                   <div style={{
                     padding: '10px 14px', borderRadius: '12px', fontSize: '14px', lineHeight: '1.6',
                     whiteSpace: 'pre-wrap', wordBreak: 'break-word',
-                    background: m.role === 'user' ? '#6C63FF' : '#FFFFFF',
+                    background: m.role === 'user' ? '#5B5FED' : '#FFFFFF',
                     color: m.role === 'user' ? '#fff' : '#1A1F36',
                     border: m.role === 'user' ? 'none' : '1px solid #E5E7EB',
                   }}>{m.content}</div>
@@ -90,7 +90,7 @@ const WechatHistory: React.FC = () => {
 };
 
 const btnStyle: React.CSSProperties = {
-  padding: '8px 20px', background: '#6C63FF', border: 'none', borderRadius: '6px',
+  padding: '8px 20px', background: '#5B5FED', border: 'none', borderRadius: '6px',
   color: '#fff', fontSize: '14px', fontWeight: 500, cursor: 'pointer',
 };