fix: surface truncation warning in PR comment, align word limit with max_tokens

- Track wasTruncated and append a visible blockquote warning to the
  posted comment so reviewers know the diff was cut off
- Raise prompt word limit from 400 → 800 to be consistent with the
  2048 max_tokens budget

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nadavis

scripts/ai-review.mjs

@@ -29,7 +29,8 @@ async function runReview() {
       return;
     }
 
-    const truncatedDiff = prDiff.length > MAX_DIFF_CHARS
+    const wasTruncated = prDiff.length > MAX_DIFF_CHARS;
+    const truncatedDiff = wasTruncated
       ? prDiff.slice(0, MAX_DIFF_CHARS) + "\n\n... [diff truncated]"
       : prDiff;
 
@@ -45,7 +46,7 @@ Review the following git diff and provide concise, actionable feedback. Focus on
 
 If the changes look good with no issues, say so briefly.
 Do NOT rewrite the code. Just review it.
-Keep your review under 400 words.
+Keep your review under 800 words.
 
 ## Git Diff:
 ${truncatedDiff}`;
@@ -65,7 +66,7 @@ ${truncatedDiff}`;
       owner: repoOwner,
       repo: repoName,
       issue_number: prNumber,
-      body: `## 🤖 Claude Code Review\n\n${review}\n\n---\n*Automated review by Claude Sonnet*`,
+      body: `## 🤖 Claude Code Review\n\n${review}${wasTruncated ? "\n\n> ⚠️ **Note:** This diff exceeded 20,000 characters and was truncated. The review above covers only the first portion of the changes." : ""}\n\n---\n*Automated review by Claude Sonnet*`,
     });
 
     console.log("Review posted successfully.");