feat: Complete type safety improvements for CLI and service layers

Implement comprehensive type annotations and mypy configuration as part
of code quality initiative. Achieve 100% type annotation coverage for
main CLI entry points and resolve Optional type inconsistencies.

## Key Improvements

### CLI Layer (100% Type Coverage)
- tddai_cli.py: Complete type annotations for all 21 functions
- cli/core.py: Full type coverage for CLI framework (20 functions)
- cli/commands/issues.py: Fixed Optional[List[str]] parameter types
- cli/commands/workspace.py: Improved type checker logic for Optional handling

### Service Layer Type Safety
- services/issue_service.py: Fixed Optional parameter type signatures
- services/project_service.py: Updated Optional type annotations
- tddai/issue_creator.py: Proper Optional[List[str]] usage
- tddai/project_manager.py: Fixed Optional parameter handling

### Mypy Configuration
- pyproject.toml: Added comprehensive mypy configuration
- Gradual adoption strategy with module-specific strictness
- Python 3.12 compatibility for proper type checking
- Incremental typing approach for legacy modules

## Technical Details
- Proper Optional vs Union type usage throughout
- Generic type annotations for collections
- Return type annotations for all public functions
- Fixed implicit Optional violations (PEP 484)
- Type checker logic improvements for better safety

## Benefits
- Improved IDE autocomplete and error detection
- Compile-time type checking for CLI commands
- Better maintainability and debugging capabilities
- Foundation for expanding type safety to remaining modules

Resolves #27 - Type safety improvements

🤖 Generated with [Claude Code](https://claude.ai/code)

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

cli/commands/issues.py

@@ -2,7 +2,7 @@
 Issue CLI commands.
 """
 
-from typing import List
+from typing import List, Optional, Any
 
 from tddai import TddaiError
 from services import IssueService
@@ -12,7 +12,7 @@ from cli.presenters import OutputFormatter, IssueView
 class IssueCommands:
     """Commands for issue operations."""
 
-    def __init__(self):
+    def __init__(self) -> None:
         self.service = IssueService()
 
     def list_issues(self) -> None:
@@ -53,8 +53,8 @@ class IssueCommands:
 
     def create_enhancement_issue(self, title: str, use_case: str,
                                technical_requirements: str = "",
-                               acceptance_criteria: List[str] = None,
-                               dependencies: List[str] = None,
+                               acceptance_criteria: Optional[List[str]] = None,
+                               dependencies: Optional[List[str]] = None,
                                priority: str = "Medium") -> None:
         """Create a structured enhancement issue."""
         try:
@@ -82,7 +82,7 @@ class IssueCommands:
         except TddaiError as e:
             OutputFormatter.exit_with_error(f"Error creating enhancement issue: {e}")
 
-    def create_from_template(self, template_file: str, **kwargs) -> None:
+    def create_from_template(self, template_file: str, **kwargs: Any) -> None:
         """Create issue from template file."""
         try:
             OutputFormatter.info(f"Creating issue from template: {template_file}")