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>

src/skill_seekers/cli/create_command.py

@@ -7,7 +7,6 @@ to appropriate scraper while maintaining full backward compatibility.
 import sys
 import logging
 import argparse
-from typing import List, Optional
 
 from skill_seekers.cli.source_detector import SourceDetector, SourceInfo
 from skill_seekers.cli.arguments.create import (
@@ -17,7 +16,6 @@ from skill_seekers.cli.arguments.create import (
 
 logger = logging.getLogger(__name__)
 
-
 class CreateCommand:
     """Unified create command implementation."""
 
@@ -28,7 +26,7 @@ class CreateCommand:
             args: Parsed command-line arguments
         """
         self.args = args
-        self.source_info: Optional[SourceInfo] = None
+        self.source_info: SourceInfo | None = None
 
     def execute(self) -> int:
         """Execute the create command.
@@ -311,7 +309,7 @@ class CreateCommand:
         finally:
             sys.argv = original_argv
 
-    def _add_common_args(self, argv: List[str]) -> None:
+    def _add_common_args(self, argv: list[str]) -> None:
         """Add common/universal arguments to argv list.
 
         Args:
@@ -367,7 +365,6 @@ class CreateCommand:
         if getattr(self.args, 'interactive_enhancement', False):
             argv.append('--interactive-enhancement')
 
-
 def main() -> int:
     """Entry point for create command.
 
@@ -510,6 +507,5 @@ Common Workflows:
     command = CreateCommand(args)
     return command.execute()
 
-
 if __name__ == '__main__':
     sys.exit(main())