feat(router): improve direct_chat fast-path and add 103 token env sync

Route explicit text-only Q&A away from Agent before page-generation rules,
and add a script to enable Router + tighter memory budgets on 103 without
changing the global deepseek-v4-pro model.

Co-authored-by: Cursor <cursoragent@cursor.com>

chat-intent-router.test.mjs

@@ -109,6 +109,25 @@ test('classifyWithRules routes greetings to direct chat', () => {
   assert.equal(result.source, 'rule');
 });
 
+test('classifyWithRules routes explicit text-only Q&A to direct chat', () => {
+  for (const text of [
+    '用三句话介绍苏州园林，不要生成页面',
+    '简要介绍一下 Rust 和 Go 的区别',
+    '推荐一个最适合第一次去的，一句话说明理由',
+  ]) {
+    const result = classifyWithRules({
+      text,
+      userMessage: {
+        role: 'user',
+        content: [{ type: 'text', text }],
+        metadata: { displayText: text },
+      },
+    });
+    assert.equal(result.route, CHAT_INTENT_ROUTE.DIRECT_CHAT, text);
+    assert.equal(result.source, 'rule', text);
+  }
+});
+
 test('classifyWithRules routes page generation to agent orchestration', () => {
   const result = classifyWithRules({
     text: '帮我做一个秋夜诗的 H5 页面',