feat: support runtime base path configuration via BASE_PATH env var

src/ui/lib/base-path.ts

@@ -1,4 +1,9 @@
 export function getBasePath(): string {
+  const runtime = (window as unknown as Record<string, unknown>)
+    .__TERMIX_BASE_PATH__ as string | undefined;
+  if (runtime) {
+    return runtime.endsWith("/") ? runtime.slice(0, -1) : runtime;
+  }
   const base = import.meta.env.BASE_URL || "/";
   if (base === "./" || base === "/") return "";
   return base.endsWith("/") ? base.slice(0, -1) : base;