Add feedback prompt back to code review comments

Restore the 👍/👎 feedback CTA to help gather signal on
code review usefulness.

plugins/code-review/commands/code-review.md

@@ -114,6 +114,8 @@ Found 3 issues:
 
 <link to file and line with full sha1 + line range for context>
 
+<sub>If this code review was useful, please react with 👍. Otherwise, react with 👎.</sub>
+
 ---
 
 - Or, if you found no issues:
@@ -124,6 +126,8 @@ Found 3 issues:
 
 No issues found. Checked for bugs and CLAUDE.md compliance.
 
+<sub>If this code review was useful, please react with 👍. Otherwise, react with 👎.</sub>
+
 ---
 
 - When linking to code, follow the following format precisely, otherwise the Markdown preview won't render correctly: https://github.com/anthropics/claude-code/blob/c21d3c10bc8e898b7ac1a2d745bdc9bc4e423afe/package.json#L10-L15