feat: allow manual Node.js path configuration (#1577)

Add ability to manually configure Node.js path for users who have
Node.js
installed but not in their system PATH.

Features:
- Browse and select custom Node.js installation folder
- Visual status indicator showing Node.js version or "Not found"
- Reset to system default PATH option
- Manual configuration option in setup banner
- Real-time Node.js status checking

closes #1050

    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Adds manual Node.js path configuration so the app works even when Node
isn’t on PATH, fulfilling #1050. Users can browse to their install,
reset to default, and see real-time status in Settings and during setup.

- New Features
- Settings: NodePathSelector to browse a Node.js folder, show
version/“Not found” status, and reset to system PATH (persists
customNodePath).
- Setup banner: manual config flow with a folder picker if Node is
already installed.
- IPC: select-node-folder, set-node-path, get-node-path; reloads env and
prepends custom path to PATH.
- Real-time Node.js status check with visual indicator (CheckCircle on
valid).
  - E2E tests for browse, reset, and valid-status display.

<!-- End of auto-generated description by cubic. -->

src/ipc/handlers/node_handlers.ts

@@ -1,10 +1,13 @@
-import { ipcMain } from "electron";
+import { ipcMain, dialog } from "electron";
 import { execSync } from "child_process";
 import { platform, arch } from "os";
 import { NodeSystemInfo } from "../ipc_types";
 import fixPath from "fix-path";
 import { runShellCommand } from "../utils/runShellCommand";
 import log from "electron-log";
+import { existsSync } from "fs";
+import { join } from "path";
+import { readSettings } from "../../main/settings";
 
 const logger = log.scope("node_handlers");
 
@@ -52,6 +55,50 @@ export function registerNodeHandlers() {
     } else {
       fixPath();
     }
+    const settings = readSettings();
+    if (settings.customNodePath) {
+      const separator = platform() === "win32" ? ";" : ":";
+      process.env.PATH = `${settings.customNodePath}${separator}${process.env.PATH}`;
+      logger.debug(
+        "Added custom Node.js path to PATH:",
+        settings.customNodePath,
+      );
+    }
     logger.debug("Reloaded env path, now:", process.env.PATH);
   });
+  ipcMain.handle("select-node-folder", async () => {
+    const result = await dialog.showOpenDialog({
+      title: "Select Node.js Installation Folder",
+      properties: ["openDirectory"],
+      message: "Select the folder where Node.js is installed",
+    });
+
+    if (result.canceled) {
+      return { path: null, canceled: true, selectedPath: null };
+    }
+
+    if (!result.filePaths[0]) {
+      return { path: null, canceled: false, selectedPath: null };
+    }
+
+    const selectedPath = result.filePaths[0];
+
+    // Verify Node.js exists in selected path
+    const nodeBinary = platform() === "win32" ? "node.exe" : "node";
+    const nodePath = join(selectedPath, nodeBinary);
+
+    if (!existsSync(nodePath)) {
+      // Check bin subdirectory (common on Unix systems)
+      const binPath = join(selectedPath, "bin", nodeBinary);
+      if (existsSync(binPath)) {
+        return {
+          path: join(selectedPath, "bin"),
+          canceled: false,
+          selectedPath,
+        };
+      }
+      return { path: null, canceled: false, selectedPath };
+    }
+    return { path: selectedPath, canceled: false, selectedPath };
+  });
 }