feat: add file growth check to code quality reviewer

Focus on whether this implementation grew or created large files,
not pre-existing file sizes in brownfield codebases.

skills/subagent-driven-development/code-quality-reviewer-prompt.md

@@ -21,5 +21,6 @@ Task tool (superpowers:code-reviewer):
 - Does each file have one clear responsibility with a well-defined interface?
 - Are units decomposed so they can be understood and tested independently?
 - Is the implementation following the file structure from the plan?
+- Did this implementation create new files that are already large, or significantly grow existing files? (Don't flag pre-existing file sizes — focus on what this change contributed.)
 
 **Code reviewer returns:** Strengths, Issues (Critical/Important/Minor), Assessment