fix(ui): default to relative paths for control UI assets

Changes the default base path from "/" to "./" so the control UI works
correctly when served under a custom basePath (e.g., /jbclawd/).

Previously, assets were referenced with absolute paths like /assets/...,
which failed when the UI was served under a subpath. With relative paths
(./assets/...), the browser resolves them relative to the HTML location,
making the UI work regardless of the configured basePath.

ui/vite.config.ts

@@ -14,7 +14,7 @@ function normalizeBase(input: string): string {
 
 export default defineConfig(({ command }) => {
   const envBase = process.env.CLAWDBOT_CONTROL_UI_BASE_PATH?.trim();
-  const base = envBase ? normalizeBase(envBase) : "/";
+  const base = envBase ? normalizeBase(envBase) : "./";
   return {
     base,
     publicDir: path.resolve(here, "public"),