Add tweakcn custom theme import

Adds a browser-local custom tweakcn theme slot while preserving the existing built-in themes.

Includes:
- tweakcn share-link import, validation, persistence, and custom theme rendering
- Custom option in Appearance and Quick Settings
- responsive/config toolbar and chat tool-card polish from follow-up review
- security hardening for bounded fetches, CSS token validation, redirect handling, and fail-closed unreadable payloads

Verification:
- OPENCLAW_LOCAL_CHECK=0 pnpm check:changed
- GitHub CI clean on 6ff13a1b33

scripts/test-projects.test-support.mjs

@@ -747,7 +747,7 @@ function classifyTarget(arg, cwd) {
   if (relative.startsWith("src/plugins/")) {
     return "plugin";
   }
-  if (relative.startsWith("ui/src/ui/")) {
+  if (relative.startsWith("ui/src/")) {
     return "ui";
   }
   if (relative.startsWith("src/utils/")) {
@@ -776,6 +776,17 @@ function resolveLightLaneIncludePatterns(kind, targetArg, cwd) {
   return null;
 }
 
+function shouldUseWholeConfigTarget(kind, targetArg, cwd) {
+  if (isVitestConfigTargetForKind(kind, targetArg, cwd)) {
+    return true;
+  }
+  if (kind !== "ui") {
+    return false;
+  }
+  const relative = toRepoRelativeTarget(targetArg, cwd);
+  return relative.startsWith("ui/src/") && !relative.startsWith("ui/src/ui/");
+}
+
 function createVitestArgs(params) {
   return [
     "exec",
@@ -956,7 +967,7 @@ export function buildVitestRunPlans(
       (kind === "default" &&
         grouped.every((targetArg) => isFileLikeTarget(toRepoRelativeTarget(targetArg, cwd))));
     const useWholeConfigTarget = grouped.some((targetArg) =>
-      isVitestConfigTargetForKind(kind, targetArg, cwd),
+      shouldUseWholeConfigTarget(kind, targetArg, cwd),
     );
     const includePatterns = useCliTargetArgs
       ? null