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/issue_fetcher.py

@@ -0,0 +1,136 @@
+"""
+Issue fetching from Gitea API.
+"""
+
+import json
+import subprocess
+from dataclasses import dataclass
+from datetime import datetime
+from typing import List, Optional, Dict, Any
+
+from .config import get_config
+from .exceptions import IssueError
+
+
+@dataclass
+class Issue:
+    """Represents a Gitea issue."""
+
+    number: int
+    title: str
+    body: str
+    state: str
+    created_at: datetime
+    updated_at: datetime
+    html_url: str
+    assignee: Optional[str] = None
+    labels: List[str] = None
+
+    def __post_init__(self):
+        if self.labels is None:
+            self.labels = []
+
+
+class IssueFetcher:
+    """Fetches issues from Gitea API."""
+
+    def __init__(self, config=None):
+        self.config = config or get_config()
+
+    def fetch_issue(self, issue_number: int) -> Issue:
+        """Fetch a specific issue by number."""
+        try:
+            result = subprocess.run(
+                ['curl', '-s', f"{self.config.issues_api_url}/{issue_number}"],
+                capture_output=True,
+                text=True,
+                check=True
+            )
+
+            if result.returncode != 0:
+                raise IssueError(f"Failed to fetch issue #{issue_number}: {result.stderr}")
+
+            issue_data = json.loads(result.stdout)
+
+            if 'message' in issue_data:
+                raise IssueError(f"Issue #{issue_number} not found: {issue_data['message']}")
+
+            return self._parse_issue(issue_data)
+
+        except subprocess.CalledProcessError as e:
+            raise IssueError(f"Failed to fetch issue #{issue_number}: {e}")
+        except json.JSONDecodeError as e:
+            raise IssueError(f"Failed to parse issue data: {e}")
+
+    def fetch_issues(self, state: str = "all") -> List[Issue]:
+        """Fetch all issues with optional state filter."""
+        try:
+            url = self.config.issues_api_url
+            if state != "all":
+                url += f"?state={state}"
+
+            result = subprocess.run(
+                ['curl', '-s', url],
+                capture_output=True,
+                text=True,
+                check=True
+            )
+
+            if result.returncode != 0:
+                raise IssueError(f"Failed to fetch issues: {result.stderr}")
+
+            issues_data = json.loads(result.stdout)
+
+            if isinstance(issues_data, dict) and 'message' in issues_data:
+                raise IssueError(f"Failed to fetch issues: {issues_data['message']}")
+
+            if not isinstance(issues_data, list):
+                raise IssueError("Invalid response format: expected list of issues")
+
+            return [self._parse_issue(issue_data) for issue_data in issues_data]
+
+        except subprocess.CalledProcessError as e:
+            raise IssueError(f"Failed to fetch issues: {e}")
+        except json.JSONDecodeError as e:
+            raise IssueError(f"Failed to parse issues data: {e}")
+
+    def fetch_open_issues(self) -> List[Issue]:
+        """Fetch only open issues."""
+        return self.fetch_issues(state="open")
+
+    def _parse_issue(self, issue_data: Dict[str, Any]) -> Issue:
+        """Parse issue data from API response."""
+        try:
+            labels = [label['name'] for label in issue_data.get('labels', [])]
+            assignee = None
+            if issue_data.get('assignee'):
+                assignee = issue_data['assignee'].get('login')
+
+            return Issue(
+                number=issue_data['number'],
+                title=issue_data['title'],
+                body=issue_data.get('body', ''),
+                state=issue_data['state'],
+                created_at=datetime.fromisoformat(issue_data['created_at'].replace('Z', '+00:00')),
+                updated_at=datetime.fromisoformat(issue_data['updated_at'].replace('Z', '+00:00')),
+                html_url=issue_data['html_url'],
+                assignee=assignee,
+                labels=labels
+            )
+        except (KeyError, ValueError) as e:
+            raise IssueError(f"Failed to parse issue data: {e}")
+
+    def get_issue_data_dict(self, issue_number: int) -> Dict[str, Any]:
+        """Get issue data as dictionary for workspace creation."""
+        issue = self.fetch_issue(issue_number)
+        return {
+            'number': issue.number,
+            'title': issue.title,
+            'body': issue.body,
+            'state': issue.state,
+            'created_at': issue.created_at.isoformat(),
+            'updated_at': issue.updated_at.isoformat(),
+            'html_url': issue.html_url,
+            'assignee': {'login': issue.assignee} if issue.assignee else None,
+            'labels': [{'name': label} for label in issue.labels]
+        }