chore: ignore local planning artifacts

Add /task_plan.md /findings.md /progress.md to .gitignore so the
planning-with-files workflow does not leak per-developer working
memory into the repo.

Author: mochengqian

.gitignore

@@ -46,3 +46,8 @@ build/
 vendor/
 
 app/dubbo-ui/dist/
+
+# planning-with-files local working memory (never commit; per-developer)
+/task_plan.md
+/findings.md
+/progress.md