refactor(config): remove redundant length check on agent target paths

selectAgentTargetPaths returns either undefined or a non-empty array,
and writeAgentInstructions already guards against empty arrays internally.

Author: fengmk2

packages/cli/src/config/bin.ts

@@ -93,7 +93,7 @@ async function main() {
         },
       });
 
-      if (selectedAgentTargetPaths && selectedAgentTargetPaths.length > 0) {
+      if (selectedAgentTargetPaths) {
         await writeAgentInstructions({
           projectRoot: root,
           targetPaths: selectedAgentTargetPaths,