fix: Complete fix for Issue #219 - All three problems resolved

**Problem #1: Large File Encoding Error** ✅ FIXED
- Add large file download support via download_url
- Detect encoding='none' for files >1MB
- Download via GitHub raw URL instead of API
- Handles ccxt/ccxt's 1.4MB CHANGELOG.md successfully

**Problem #2: Missing CLI Enhancement Flags** ✅ FIXED
- Add --enhance, --enhance-local, --api-key to main.py github_parser
- Add flag forwarding in CLI dispatcher
- Fixes 'unrecognized arguments' error
- Users can now use: skill-seekers github --repo owner/repo --enhance-local

**Problem #3: Custom API Endpoint Support** ✅ FIXED
- Support ANTHROPIC_BASE_URL environment variable
- Support ANTHROPIC_AUTH_TOKEN (alternative to ANTHROPIC_API_KEY)
- Fix ThinkingBlock.text error with newer Anthropic SDK
- Find TextBlock in response content array (handles thinking blocks)

**Changes**:
- src/skill_seekers/cli/enhance_skill.py:
  - Support custom base_url parameter
  - Support both ANTHROPIC_API_KEY and ANTHROPIC_AUTH_TOKEN
  - Iterate through content blocks to find text (handles ThinkingBlock)

- src/skill_seekers/cli/main.py:
  - Add --enhance, --enhance-local, --api-key to github_parser
  - Forward flags to github_scraper.py in dispatcher

- src/skill_seekers/cli/github_scraper.py:
  - Add large file detection (encoding=None/"none")
  - Download via download_url with requests
  - Log file size and download progress

- tests/test_github_scraper.py:
  - Add test_get_file_content_large_file
  - Add test_extract_changelog_large_file
  - All 31 tests passing ✅

**Credits**:
- Thanks to @XGCoder for detailed bug report
- Thanks to @gorquan for local fixes and guidance

Fixes #219

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/skill_seekers/cli/github_scraper.py

@@ -355,6 +355,26 @@ class GitHubScraper:
                     logger.warning(f"Symlink {file_path} has no target")
                     return None
 
+            # Handle large files (encoding="none") - download via URL
+            # GitHub API doesn't base64-encode files >1MB
+            if hasattr(content, 'encoding') and content.encoding in [None, "none"]:
+                download_url = getattr(content, 'download_url', None)
+                file_size = getattr(content, 'size', 0)
+
+                if download_url:
+                    logger.info(f"File {file_path} is large ({file_size:,} bytes), downloading via URL...")
+                    try:
+                        import requests
+                        response = requests.get(download_url, timeout=30)
+                        response.raise_for_status()
+                        return response.text
+                    except Exception as e:
+                        logger.warning(f"Failed to download {file_path} from {download_url}: {e}")
+                        return None
+                else:
+                    logger.warning(f"File {file_path} has no download URL (encoding={content.encoding})")
+                    return None
+
             # Handle regular files - decode content
             try:
                 if isinstance(content.decoded_content, bytes):