feat: route staged scene skills through runtime

Add registry-driven scene routing and multi-root skill loading so fault-details and 95598 scene skills can be triggered from natural language while still running through the browser-backed runtime.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/compat/runtime.rs

@@ -146,7 +146,7 @@ pub async fn execute_task_with_provider(
     instruction: &str,
     task_context: &CompatTaskContext,
     config: ZeroClawConfig,
-    skills_dir: PathBuf,
+    skills_dir: Vec<PathBuf>,
     settings: SgClawSettings,
 ) -> Result<String, PipeError> {
     let engine = RuntimeEngine::new(settings.runtime_profile);