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_parser_sync.py

@@ -6,8 +6,6 @@ the same arguments as the standalone scraper modules. This prevents the
 """
 
 import argparse
-import pytest
-
 
 class TestScrapeParserSync:
     """Ensure scrape_parser has all arguments from doc_scraper."""
@@ -87,7 +85,6 @@ class TestScrapeParserSync:
         for arg in required_args:
             assert arg in arg_dests, f"Required argument '{arg}' missing from scrape parser"
 
-
 class TestGitHubParserSync:
     """Ensure github_parser has all arguments from github_scraper."""
 
@@ -131,7 +128,6 @@ class TestGitHubParserSync:
         assert not missing, f"github_parser missing arguments: {missing}"
         assert not extra, f"github_parser has extra arguments not in github_scraper: {extra}"
 
-
 class TestUnifiedCLI:
     """Test the unified CLI main parser."""