fix: harden doctor install checks

src/commands/doctor-install.ts

@@ -0,0 +1,39 @@
+import fs from "node:fs";
+import path from "node:path";
+
+import { note } from "../terminal/note.js";
+
+export function noteSourceInstallIssues(root: string | null) {
+  if (!root) return;
+
+  const workspaceMarker = path.join(root, "pnpm-workspace.yaml");
+  if (!fs.existsSync(workspaceMarker)) return;
+
+  const warnings: string[] = [];
+  const nodeModules = path.join(root, "node_modules");
+  const pnpmStore = path.join(nodeModules, ".pnpm");
+  const tsxBin = path.join(nodeModules, ".bin", "tsx");
+  const srcEntry = path.join(root, "src", "entry.ts");
+
+  if (fs.existsSync(nodeModules) && !fs.existsSync(pnpmStore)) {
+    warnings.push(
+      "- node_modules was not installed by pnpm (missing node_modules/.pnpm). Run: pnpm install",
+    );
+  }
+
+  if (fs.existsSync(path.join(root, "package-lock.json"))) {
+    warnings.push(
+      "- package-lock.json present in a pnpm workspace. If you ran npm install, remove it and reinstall with pnpm.",
+    );
+  }
+
+  if (fs.existsSync(srcEntry) && !fs.existsSync(tsxBin)) {
+    warnings.push(
+      "- tsx binary is missing for source runs. Run: pnpm install",
+    );
+  }
+
+  if (warnings.length > 0) {
+    note(warnings.join("\n"), "Install");
+  }
+}