fix: Resolve all linting errors from ruff

Fix 145 linting errors across CLI refactor code:

Type annotation modernization (Python 3.9+):
- Replace typing.Dict with dict
- Replace typing.List with list
- Replace typing.Set with set
- Replace Optional[X] with X | None

Code quality improvements:
- Remove trailing whitespace (W291)
- Remove whitespace from blank lines (W293)
- Remove unused imports (F401)
- Use dictionary lookup instead of if-elif chains (SIM116)
- Combine nested if statements (SIM102)

Files fixed (45 files):
- src/skill_seekers/cli/arguments/*.py (10 files)
- src/skill_seekers/cli/parsers/*.py (24 files)
- src/skill_seekers/cli/presets/*.py (4 files)
- src/skill_seekers/cli/create_command.py
- src/skill_seekers/cli/source_detector.py
- src/skill_seekers/cli/github_scraper.py
- tests/test_*.py (5 test files)

All files now pass ruff linting checks.

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

tests/test_cli_refactor_e2e.py

@@ -12,9 +12,6 @@ These tests verify that the unified CLI architecture works correctly:
 import pytest
 import subprocess
 import argparse
-import sys
-from pathlib import Path
-
 
 class TestParserSync:
     """E2E tests for parser synchronization (Issue #285)."""
@@ -77,7 +74,6 @@ class TestParserSync:
         for flag in expected_flags:
             assert flag in result.stdout, f"Help should show {flag} flag"
 
-
 class TestPresetSystem:
     """E2E tests for preset system (Issue #268)."""
 
@@ -141,7 +137,6 @@ class TestPresetSystem:
         assert "DEPRECATED" in output, "Should show deprecation warning"
         assert "--preset comprehensive" in output, "Should suggest alternative"
 
-
 class TestBackwardCompatibility:
     """E2E tests for backward compatibility."""
 
@@ -185,7 +180,6 @@ class TestBackwardCompatibility:
             assert flag in unified_result.stdout, f"Unified should have {flag}"
             assert flag in standalone_result.stdout, f"Standalone should have {flag}"
 
-
 class TestProgrammaticAPI:
     """Test that the shared argument functions work programmatically."""
 
@@ -227,7 +221,6 @@ class TestProgrammaticAPI:
         # Note: enhance_level is not part of AnalysisPreset anymore.
         # It's controlled separately via --enhance-level flag (default 2)
 
-
 class TestIntegration:
     """Integration tests for the complete flow."""
 
@@ -278,7 +271,6 @@ class TestIntegration:
         assert "--preset" in result.stdout, "Should show --preset flag"
         assert "DEFAULT" in result.stdout or "default" in result.stdout, "Should indicate default preset"
 
-
 class TestE2EWorkflow:
     """End-to-end workflow tests."""
 
@@ -322,6 +314,5 @@ class TestE2EWorkflow:
         assert "--preset" in result.stdout, "Should have --preset flag"
         assert "unrecognized arguments" not in result.stderr.lower()
 
-
 if __name__ == "__main__":
     pytest.main([__file__, "-v", "-s"])