fix: use getRootDir() for package.json in self-update detection

In Electron, process.cwd() points to the system directory instead of
the app root, causing getProxyInfo() to return version "unknown". This
made update detection always fail since "1.0.x" < "unknown" lexically.

Add rootDir to PathConfig and getRootDir() helper so Electron can pass
app.getAppPath() for correct package.json resolution.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/paths.ts

@@ -8,6 +8,7 @@
 import { resolve } from "path";
 
 interface PathConfig {
+  rootDir: string;
   configDir: string;
   dataDir: string;
   binDir: string;
@@ -25,6 +26,11 @@ export function setPaths(config: PathConfig): void {
   _paths = config;
 }
 
+/** App root directory (where package.json lives). */
+export function getRootDir(): string {
+  return _paths?.rootDir ?? process.cwd();
+}
+
 /** Directory containing YAML config files. */
 export function getConfigDir(): string {
   return _paths?.configDir ?? resolve(process.cwd(), "config");

src/self-update.ts

@@ -9,7 +9,7 @@ import { execFile, execFileSync } from "child_process";
 import { existsSync, readFileSync } from "fs";
 import { resolve } from "path";
 import { promisify } from "util";
-import { isEmbedded } from "./paths.js";
+import { getRootDir, isEmbedded } from "./paths.js";
 
 const execFileAsync = promisify(execFile);
 
@@ -58,7 +58,7 @@ let _checking = false;
 export function getProxyInfo(): ProxyInfo {
   let version = "unknown";
   try {
-    const pkg = JSON.parse(readFileSync(resolve(process.cwd(), "package.json"), "utf-8")) as { version?: string };
+    const pkg = JSON.parse(readFileSync(resolve(getRootDir(), "package.json"), "utf-8")) as { version?: string };
     version = pkg.version ?? "unknown";
   } catch { /* ignore */ }