fix: Fix list comprehension variable names (NameError in CI)

Fixed incorrect variable names in list comprehensions that were causing
NameError in CI (Python 3.11/3.12):

Critical fixes:
- tests/test_markdown_parsing.py: 'l' → 'link' in list comprehension
- src/skill_seekers/cli/pdf_extractor_poc.py: 'l' → 'line' (2 occurrences)

Additional auto-lint fixes:
- Removed unused imports in llms_txt_downloader.py, llms_txt_parser.py
- Fixed comparison operators in config files
- Fixed list comprehension in other files

All tests now pass in CI.

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

tests/test_install_agent.py

@@ -371,7 +371,7 @@ class TestInstallToAllAgents:
 
                 # With force - should succeed
                 results_with_force = install_to_all_agents(self.skill_dir, force=True)
-                for _agent_name, (success, message) in results_with_force.items():
+                for _agent_name, (success, _message) in results_with_force.items():
                     assert success is True
 
     def test_install_to_all_returns_results(self):