feat(prompt): instruct agents to offload out-of-scope work via SuggestImprovement

src/ClaudeDo.Data/PromptFiles.cs

@@ -75,6 +75,11 @@ public static class PromptFiles
         - Prefer three similar lines over a premature abstraction. Don't build for
           hypothetical future needs.
 
+        ## Out-of-scope improvements
+        If you notice worthwhile work that is genuinely outside this task's scope
+        (a refactor, a follow-up, tech debt), do NOT do it here. File it with
+        SuggestImprovement(title, description) and stay focused on the task at hand.
+
         ## Working in the repo
         - Read a file before editing it. Match the conventions already in this codebase —
           they override generic defaults.