feat(lanes): extract skills-install lib, add POST /api/skills/install (F4)

server/routes/skills.js

@@ -0,0 +1,28 @@
+/**
+ * @file Machine-wide (not lane-scoped) skill installation.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+const { Router } = require("express");
+const path = require("node:path");
+const { installShipFeatureLaneSkill } = require("../lib/skills-install");
+const { sameOriginGuard } = require("./run");
+
+const router = Router();
+
+/** This server's own checkout root — server/routes/skills.js is two levels
+ *  under it (server/routes/), same computation bin/ccam.js's REPO_ROOT
+ *  already does from its own location. */
+const REPO_ROOT = path.resolve(__dirname, "..", "..");
+
+router.post("/install", sameOriginGuard, (req, res) => {
+  try {
+    res.json(installShipFeatureLaneSkill({ repoRoot: REPO_ROOT }));
+  } catch (err) {
+    if (err.code === "ENOSKILLSRC") {
+      return res.status(400).json({ error: { code: err.code, message: err.message } });
+    }
+    res.status(500).json({ error: { code: err.code || "ERUNTIME", message: err.message } });
+  }
+});
+
+module.exports = router;