fix: address review feedback on architecture guidance

- Define DONE_WITH_CONCERNS handling in SDD controller flow
- Make implementer action explicit when file grows beyond plan intent
- Reword writing-plans file size reasoning (avoid tooling-artifact language)
- Add decomposition awareness to code quality reviewer prompt

skills/subagent-driven-development/implementer-prompt.md

@@ -47,8 +47,8 @@ Task tool (general-purpose):
     reliable when files are focused. Keep this in mind:
     - Follow the file structure defined in the plan
     - Each file should have one clear responsibility with a well-defined interface
-    - If a file you're creating is growing beyond the plan's intent, consider whether
-      it should be split into smaller units with clear boundaries
+    - If a file you're creating is growing beyond the plan's intent, stop and report
+      it as DONE_WITH_CONCERNS — don't split files on your own without plan guidance
     - If an existing file you're modifying is already large or tangled, work carefully
       and note it as a concern in your report
     - In existing codebases, follow established patterns. Improve code you're touching