feat: implement tddai Python library for TDD workspace management

- Create comprehensive tddai package with workspace, issue fetcher, and test generator modules
- Add Python CLI interface (tddai_cli.py) to replace complex Makefile shell logic
- Update Makefile targets to use Python CLI for better maintainability
- Implement proper behavior-based tests instead of file existence checks
- Add workspace lifecycle management (create, active, finish, cleanup)
- Add issue fetching from Gitea API with error handling
- Add comprehensive test coverage with 19 passing tests
- Support environment variable configuration for different deployments

This addresses issue #11: Setup TDD workspace infrastructure
All tests pass and the system achieves green state before commit.

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

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

tddai/__init__.py

@@ -0,0 +1,26 @@
+"""
+tddai - Test-Driven Development with AI Support
+
+A Python library for managing issue-driven TDD workflows with AI assistance.
+Provides workspace management, test generation, and issue integration.
+"""
+
+from .workspace import WorkspaceManager, Workspace, WorkspaceStatus
+from .issue_fetcher import IssueFetcher, Issue
+from .test_generator import TestGenerator
+from .exceptions import TddaiError, WorkspaceError, IssueError, ConfigurationError, TestGenerationError
+
+__version__ = "0.1.0"
+__all__ = [
+    "WorkspaceManager",
+    "Workspace",
+    "WorkspaceStatus",
+    "IssueFetcher",
+    "Issue",
+    "TestGenerator",
+    "TddaiError",
+    "WorkspaceError",
+    "IssueError",
+    "ConfigurationError",
+    "TestGenerationError",
+]