feat(gui): Electron desktop with embedded core, tray, autostart, win/linux packaging

- cmd/gui: Electron shell (Clash-Verge style) embedding the full WebUI 1:1
  - embedded llmsproxy core (luajit) with auto-generated profile
  - key stored in keys[] (non-seed) so no replace-the-key warning
  - gw_key cookie injection: web UI works without login
  - side-rail toggles for autostart / silent start
  - system tray with status + controls, silent start (--silent)
  - win cross-build (mingw luajit exe + dll) / deb / AppImage via electron-builder
- Makefile: build / gui / gui-dist / gui-deb / gui-win targets
- README: desktop GUI section
- lua(adapter): opencode normalizes non-whitelisted roles to system

cmd/gui/scripts/prepare-core.js

@@ -0,0 +1,74 @@
+#!/usr/bin/env node
+// Build the embedded llmsproxy core(s) for the GUI package.
+//   node prepare-core.js        -> linux (native, luajit) + win (cross, best effort)
+//   node prepare-core.js linux  -> linux only
+//   node prepare-core.js win    -> win only
+const { execFileSync } = require("child_process");
+const fs = require("fs");
+const path = require("path");
+
+const guiDir = __dirname.replace(/scripts$/, "");
+const binDir = path.join(guiDir, "bin");
+const projectRoot = path.join(guiDir, "..", "..");
+
+function buildLinux() {
+  const out = path.join(binDir, "llmsproxy");
+  console.log("[prepare-core] building llmsproxy (linux/luajit)...");
+  fs.mkdirSync(binDir, { recursive: true });
+  execFileSync(
+    "go",
+    ["build", "-tags", "luajit", "-trimpath", "-o", out, "./cmd/llmsproxy"],
+    { cwd: projectRoot, stdio: "inherit" },
+  );
+  return out;
+}
+
+function buildWin() {
+  const out = path.join(binDir, "llmsproxy.exe");
+  console.log(
+    "[prepare-core] cross-building llmsproxy.exe (windows/amd64, luajit)...",
+  );
+  fs.mkdirSync(binDir, { recursive: true });
+  const cc = process.env.MINGW_CC || "x86_64-w64-mingw32-gcc";
+  // friendly hint when the mingw cross-compiler is missing
+  try {
+    execFileSync(cc + " --version", { shell: true, stdio: "ignore" });
+  } catch (e) {
+    console.error(
+      "[prepare-core] MISSING mingw-w64 cross-compiler (" + cc + ").",
+    );
+    console.error("  Install it:  sudo apt install gcc-mingw-w64-x86-64");
+    console.error("  Then re-run:  npm run core:win  (or make gui-win)");
+    process.exit(1);
+  }
+  execFileSync(
+    "go",
+    ["build", "-tags", "luajit", "-trimpath", "-o", out, "./cmd/llmsproxy"],
+    {
+      cwd: projectRoot,
+      stdio: "inherit",
+      env: Object.assign({}, process.env, {
+        GOOS: "windows",
+        GOARCH: "amd64",
+        CGO_ENABLED: "1",
+        CC: cc,
+      }),
+    },
+  );
+  return out;
+}
+
+const which = process.argv[2] || "both";
+const results = [];
+try {
+  if (which === "linux" || which === "both") results.push(buildLinux());
+} catch (e) {
+  console.error("[prepare-core] linux build failed:", e.message);
+}
+try {
+  if (which === "win" || which === "both") results.push(buildWin());
+} catch (e) {
+  console.error("[prepare-core] win build failed:", e.message);
+}
+if (results.length === 0) process.exit(1);
+results.forEach((p) => console.log("[prepare-core] core ready: " + p));