feat: add llms.txt downloader with error handling

cli/llms_txt_downloader.py

@@ -0,0 +1,43 @@
+"""ABOUTME: Downloads llms.txt files from documentation URLs with error handling"""
+"""ABOUTME: Handles timeouts, retries, and validates content before returning"""
+
+import requests
+from typing import Optional
+
+class LlmsTxtDownloader:
+    """Download llms.txt content from URLs"""
+
+    def __init__(self, url: str, timeout: int = 30):
+        self.url = url
+        self.timeout = timeout
+
+    def download(self) -> Optional[str]:
+        """
+        Download llms.txt content.
+
+        Returns:
+            String content or None if download fails
+        """
+        try:
+            headers = {
+                'User-Agent': 'Skill-Seekers-llms.txt-Reader/1.0'
+            }
+
+            response = requests.get(
+                self.url,
+                headers=headers,
+                timeout=self.timeout
+            )
+            response.raise_for_status()
+
+            content = response.text
+
+            # Validate content is not empty and looks like markdown
+            if len(content) < 100:
+                return None
+
+            return content
+
+        except requests.RequestException as e:
+            print(f"❌ Failed to download {self.url}: {e}")
+            return None