feat(ncp): doctor checks Node meets Vite's minimum (20.19+)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

management/ncp.py

@@ -485,8 +485,23 @@ def cmd_doctor() -> None:
         except OSError:
             return ""
 
+    def node_ok(ver: str) -> bool:
+        # Vite needs Node 20.19+ (or 22.12+); Debian's apt 'nodejs' is EOL 18.
+        try:
+            parts = ver.lstrip("v").split(".")
+            major, minor = int(parts[0]), int(parts[1])
+        except (ValueError, IndexError):
+            return False
+        return major >= 21 or (major == 20 and minor >= 19)
+
     node, npm_path = shutil.which("node"), npm()
-    mark(bool(node), f"Node installed ({version(node)})", "Node missing")
+    node_ver = version(node)
+    mark(bool(node), f"Node installed ({node_ver})", "Node missing")
+    if node:
+        mark(node_ok(node_ver),
+             f"Node version OK ({node_ver} >= 20.19, Vite requirement)",
+             f"Node {node_ver} too old for Vite (needs 20.19+). Install Node 20 "
+             f"(re-run ./install.sh, or NodeSource), then rebuild with: ncp update")
     mark(bool(npm_path), f"npm installed ({version(npm_path)})", "npm missing")
     mark((FRONTEND_DIR / "node_modules").is_dir(),
          "Frontend node_modules installed",