fix: resolve CI/CD linting issues

- Remove unused imports (F401) from analyzers and test files
- Remove unused typing imports (Any, Dict, List, Optional)
- Remove unused datetime imports
- Remove unused rich.columns import
- Remove unused pytest imports in test files

tests/test_formatters.py

@@ -1,14 +1,8 @@
 import json
-from datetime import datetime
 from src.formatters.json_formatter import JSONFormatter
 from src.formatters.markdown_formatter import MarkdownFormatter
 from src.formatters.html_formatter import HTMLFormatter
-from src.models.data_structures import (
-    CommitAnalysis,
-    CodeChurnAnalysis,
-    RiskyCommitAnalysis,
-    VelocityAnalysis,
-)
+from src.models.data_structures import CommitAnalysis
 
 
 class TestJSONFormatter: