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_create_arguments.py

@@ -6,7 +6,6 @@ Tests the three-tier argument system:
 3. Advanced arguments
 """
 
-import pytest
 from skill_seekers.cli.arguments.create import (
     UNIVERSAL_ARGUMENTS,
     WEB_ARGUMENTS,
@@ -20,7 +19,6 @@ from skill_seekers.cli.arguments.create import (
     add_create_arguments,
 )
 
-
 class TestUniversalArguments:
     """Test universal argument definitions."""
 
@@ -51,7 +49,6 @@ class TestUniversalArguments:
             assert 'kwargs' in arg_def
             assert 'help' in arg_def['kwargs']
 
-
 class TestSourceSpecificArguments:
     """Test source-specific argument definitions."""
 
@@ -96,7 +93,6 @@ class TestSourceSpecificArguments:
                         assert flag not in all_flags, f"Duplicate flag: {flag}"
                         all_flags.add(flag)
 
-
 class TestAdvancedArguments:
     """Test advanced/rare argument definitions."""
 
@@ -106,7 +102,6 @@ class TestAdvancedArguments:
         assert 'no_rate_limit' in ADVANCED_ARGUMENTS
         assert 'interactive_enhancement' in ADVANCED_ARGUMENTS
 
-
 class TestArgumentHelpers:
     """Test helper functions."""
 
@@ -148,7 +143,6 @@ class TestArgumentHelpers:
         args = get_source_specific_arguments('unknown')
         assert args == {}
 
-
 class TestCompatibleArguments:
     """Test compatible argument detection."""
 
@@ -217,7 +211,6 @@ class TestCompatibleArguments:
         assert 'repo' not in compatible
         assert 'directory' not in compatible
 
-
 class TestAddCreateArguments:
     """Test add_create_arguments function."""
 
@@ -284,7 +277,6 @@ class TestAddCreateArguments:
             args = parser.parse_args(['some_source'])
             assert args.source == 'some_source'
 
-
 class TestNoDuplicates:
     """Test that there are no duplicate arguments across tiers."""
 
@@ -320,7 +312,6 @@ class TestNoDuplicates:
         assert len(github_flags & pdf_flags) == 0
         assert len(local_flags & pdf_flags) == 0
 
-
 class TestArgumentQuality:
     """Test argument definition quality."""