feat: add folder picker and target_url input to Web UI

- Add /select-folder and /select-file APIs using PowerShell dialogs
- Add --target-url parameter to CLI for explicit target URL override
- Redesign Web UI with folder browse buttons for all path inputs
- Add target_url optional input field for specifying target page URL
- Auto-fill scene-id from selected folder name

🤖 Generated with [Qoder][https://qoder.com]

frontend/scene-generator/server.js

@@ -4,6 +4,7 @@
 const http = require("http");
 const fs = require("fs");
 const path = require("path");
+const { spawn } = require("child_process");
 const { loadConfig, getDefaults } = require("./config-loader");
 const { analyzeScene } = require("./llm-client");
 const { runGenerator, readDirectory } = require("./generator-runner");
@@ -126,7 +127,7 @@ async function handleGenerate(req, res) {
     return;
   }
 
-  const { sourceDir, sceneId, sceneName, sceneKind, outputRoot, lessons } = body;
+  const { sourceDir, sceneId, sceneName, sceneKind, targetUrl, outputRoot, lessons } = body;
   if (!sourceDir || !sceneId || !sceneName || !outputRoot || !lessons) {
     res.writeHead(400, { "Content-Type": "application/json" });
     res.end(
@@ -142,7 +143,7 @@ async function handleGenerate(req, res) {
 
   try {
     await runGenerator(
-      { sourceDir, sceneId, sceneName, sceneKind, outputRoot, lessons },
+      { sourceDir, sceneId, sceneName, sceneKind, targetUrl, outputRoot, lessons },
       sseWriter,
       config.projectRoot
     );
@@ -166,6 +167,116 @@ function handleHealth(req, res) {
   );
 }
 
+/**
+ * Open a native Windows folder selection dialog using PowerShell.
+ * Returns the selected folder path or null if cancelled.
+ */
+function openFolderDialog(defaultPath) {
+  return new Promise((resolve) => {
+    const psScript = `
+Add-Type -AssemblyName System.Windows.Forms
+$dialog = New-Object System.Windows.Forms.FolderBrowserDialog
+$dialog.Description = "选择文件夹"
+$dialog.ShowNewFolderButton = true
+${defaultPath ? `$dialog.SelectedPath = '${defaultPath.replace(/'/g, "''")}'` : ""}
+if ($dialog.ShowDialog() -eq 'OK') {
+  Write-Output $dialog.SelectedPath
+}
+`.trim();
+
+    const ps = spawn("powershell.exe", [
+      "-NoProfile",
+      "-NonInteractive",
+      "-Command",
+      psScript,
+    ]);
+
+    let output = "";
+    let error = "";
+
+    ps.stdout.on("data", (data) => {
+      output += data.toString();
+    });
+
+    ps.stderr.on("data", (data) => {
+      error += data.toString();
+    });
+
+    ps.on("close", (code) => {
+      if (code === 0 && output.trim()) {
+        resolve(output.trim());
+      } else {
+        resolve(null);
+      }
+    });
+
+    ps.on("error", () => {
+      resolve(null);
+    });
+  });
+}
+
+async function handleSelectFolder(req, res) {
+  let body = {};
+  try {
+    body = await parseBody(req);
+  } catch {
+    // ignore parse error, use empty body
+  }
+
+  const selectedPath = await openFolderDialog(body.defaultPath || "");
+  res.writeHead(200, { "Content-Type": "application/json" });
+  res.end(JSON.stringify({ path: selectedPath }));
+}
+
+async function handleSelectFile(req, res) {
+  let body = {};
+  try {
+    body = await parseBody(req);
+  } catch {
+    // ignore parse error
+  }
+
+  const filter = body.filter || "所有文件 (*.*)|*.*";
+  const psScript = `
+Add-Type -AssemblyName System.Windows.Forms
+$dialog = New-Object System.Windows.Forms.OpenFileDialog
+$dialog.Filter = '${filter}'
+$dialog.Title = "选择文件"
+${body.defaultPath ? `$dialog.InitialDirectory = '${body.defaultPath.replace(/'/g, "''")}'` : ""}
+if ($dialog.ShowDialog() -eq 'OK') {
+  Write-Output $dialog.FileName
+}
+`.trim();
+
+  return new Promise((resolve) => {
+    const ps = spawn("powershell.exe", [
+      "-NoProfile",
+      "-NonInteractive",
+      "-Command",
+      psScript,
+    ]);
+
+    let output = "";
+
+    ps.stdout.on("data", (data) => {
+      output += data.toString();
+    });
+
+    ps.on("close", (code) => {
+      res.writeHead(200, { "Content-Type": "application/json" });
+      res.end(JSON.stringify({ path: code === 0 && output.trim() ? output.trim() : null }));
+      resolve();
+    });
+
+    ps.on("error", () => {
+      res.writeHead(200, { "Content-Type": "application/json" });
+      res.end(JSON.stringify({ path: null }));
+      resolve();
+    });
+  });
+}
+
 const server = http.createServer(async (req, res) => {
   const url = new URL(req.url, `http://${req.headers.host}`);
   const pathname = url.pathname;
@@ -187,6 +298,10 @@ const server = http.createServer(async (req, res) => {
       await handleAnalyze(req, res);
     } else if (pathname === "/generate" && req.method === "POST") {
       await handleGenerate(req, res);
+    } else if (pathname === "/select-folder" && req.method === "POST") {
+      await handleSelectFolder(req, res);
+    } else if (pathname === "/select-file" && req.method === "POST") {
+      await handleSelectFile(req, res);
     } else if (pathname === "/" || pathname === "/index.html") {
       serveStatic(res, path.join(__dirname, "sg_scene_generator.html"));
     } else {