feat: 可配置方案引擎通用原型（Mock 检索）

需求未定稿时可先跑通追问/判定/出方案；槽位与判定树外置 YAML，后续可接 Ragflow。

Co-authored-by: haijd <haijd@163.com>

engine/app/static/app.js

@@ -0,0 +1,73 @@
+let sessionId = null;
+
+const logEl = document.getElementById("log");
+const slotsEl = document.getElementById("slots");
+const schemeEl = document.getElementById("scheme");
+const metaEl = document.getElementById("meta");
+const form = document.getElementById("form");
+const input = document.getElementById("input");
+const resetBtn = document.getElementById("reset");
+
+function addBubble(role, text) {
+  const div = document.createElement("div");
+  div.className = `bubble ${role}`;
+  div.textContent = text;
+  logEl.appendChild(div);
+  logEl.scrollTop = logEl.scrollHeight;
+}
+
+async function ensureSession() {
+  if (sessionId) return sessionId;
+  const res = await fetch("/api/sessions", { method: "POST" });
+  const data = await res.json();
+  sessionId = data.session_id;
+  metaEl.textContent = `session: ${sessionId.slice(0, 8)}…`;
+  return sessionId;
+}
+
+async function sendMessage(message) {
+  await ensureSession();
+  addBubble("user", message);
+  const res = await fetch("/api/chat", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ session_id: sessionId, message }),
+  });
+  if (!res.ok) {
+    addBubble("sys", `错误：${res.status}`);
+    return;
+  }
+  const data = await res.json();
+  addBubble("bot", data.reply);
+  slotsEl.textContent = JSON.stringify(data.slots || {}, null, 2);
+  schemeEl.textContent = data.scheme
+    ? JSON.stringify(data.scheme, null, 2)
+    : "尚未生成";
+  metaEl.textContent = `session: ${sessionId.slice(0, 8)}… · phase: ${data.phase}`;
+}
+
+form.addEventListener("submit", async (e) => {
+  e.preventDefault();
+  const text = input.value.trim();
+  if (!text) return;
+  input.value = "";
+  form.querySelector("button").disabled = true;
+  try {
+    await sendMessage(text);
+  } finally {
+    form.querySelector("button").disabled = false;
+    input.focus();
+  }
+});
+
+resetBtn.addEventListener("click", () => {
+  sessionId = null;
+  logEl.innerHTML = "";
+  slotsEl.textContent = "{}";
+  schemeEl.textContent = "尚未生成";
+  metaEl.textContent = "";
+  addBubble("bot", "新会话已开始。可以直接说场景，例如：「产线检测，偏向 B 类」。");
+  input.focus();
+});
+
+addBubble("bot", "你好，我是鲜境方案引擎原型。先收集几个关键信息，再给出产品组合草稿。\n试试：「我们在户外做监测，指标还不确定」。");