fix: Strip ANSI color sequences from tool output

Add stripAnsiCodes function to sanitizer and apply it in formatResultContent
to remove terminal color escape codes (e.g., [1;33m for yellow/bold) from
tool output before displaying it in GitHub comments.

This ensures clean, readable output without raw ANSI escape sequences
appearing in the formatted tool results.

src/entrypoints/format-turns.ts

@@ -2,6 +2,7 @@
 
 import { readFileSync, existsSync } from "fs";
 import { exit } from "process";
+import { stripAnsiCodes } from "../github/utils/sanitizer";
 
 export type ToolUse = {
   type: string;
@@ -172,6 +173,9 @@ export function formatResultContent(content: any): string {
     contentStr = String(content).trim();
   }
 
+  // Strip ANSI escape codes from terminal output
+  contentStr = stripAnsiCodes(contentStr);
+
   // Truncate very long results
   if (contentStr.length > 3000) {
     contentStr = contentStr.substring(0, 2997) + "...";

src/github/utils/sanitizer.ts

@@ -1,3 +1,11 @@
+export function stripAnsiCodes(content: string): string {
+  // Matches ANSI escape sequences:
+  // - \x1B[ (CSI) followed by parameters and a final byte
+  // - \x1B followed by single-character sequences
+  // Common sequences: \x1B[1;33m (colors), \x1B[0m (reset), \x1B[K (clear line)
+  return content.replace(/\x1B(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])/g, "");
+}
+
 export function stripInvisibleCharacters(content: string): string {
   content = content.replace(/[\u200B\u200C\u200D\uFEFF]/g, "");
   content = content.replace(