refactor: Separate CLI presentation from core business logic

Complete architectural separation of concerns implementing clean layered design:

• Services Layer: Pure business logic isolated from presentation
  - WorkspaceService: TDD workspace operations
  - IssueService: Issue management and creation
  - ProjectService: Project management and milestones
  - ExportService: Unix-friendly data export

• CLI Layer: Clean presentation with command/presenter separation
  - Commands delegate to services for all business operations
  - Presenters handle formatted output and error messaging
  - Framework provides unified interface

• Benefits:
  - Eliminates mixed concerns in 943-line CLI monolith
  - Enables easier testing and maintenance
  - Preserves all existing functionality and Unix pipeline compatibility
  - Provides foundation for future CLI development

Resolves issue #20: CLI separation from core logic

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

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

services/workspace_service.py

@@ -0,0 +1,116 @@
+"""
+Workspace service - business logic for TDD workspace operations.
+"""
+
+from typing import Optional, Dict, Any
+from pathlib import Path
+
+from tddai import WorkspaceManager, IssueFetcher, WorkspaceStatus, TddaiError
+
+
+class WorkspaceInfo:
+    """Value object for workspace information."""
+
+    def __init__(self, status: WorkspaceStatus, workspace=None):
+        self.status = status
+        self.workspace = workspace
+
+    @property
+    def is_clean(self) -> bool:
+        return self.status == WorkspaceStatus.CLEAN
+
+    @property
+    def is_dirty(self) -> bool:
+        return self.status == WorkspaceStatus.DIRTY
+
+    @property
+    def is_active(self) -> bool:
+        return self.status == WorkspaceStatus.ACTIVE
+
+    def get_test_files(self) -> list:
+        """Get list of test files in workspace."""
+        if not self.workspace or not self.workspace.tests_dir.exists():
+            return []
+        return list(self.workspace.tests_dir.glob("*.py"))
+
+
+class WorkspaceService:
+    """Service for workspace operations."""
+
+    def __init__(self):
+        self.workspace_manager = WorkspaceManager()
+        self.issue_fetcher = IssueFetcher()
+
+    def get_workspace_info(self) -> WorkspaceInfo:
+        """Get current workspace information."""
+        status = self.workspace_manager.get_status()
+        workspace = None
+
+        if status == WorkspaceStatus.ACTIVE:
+            workspace = self.workspace_manager.get_current_workspace()
+
+        return WorkspaceInfo(status, workspace)
+
+    def start_issue_workspace(self, issue_number: int) -> WorkspaceInfo:
+        """Start working on an issue.
+
+        Returns:
+            WorkspaceInfo with the created workspace
+
+        Raises:
+            TddaiError: If workspace already active or issue cannot be fetched
+        """
+        # Check if workspace already active
+        current_info = self.get_workspace_info()
+        if current_info.is_active:
+            raise TddaiError(f"Already working on issue #{current_info.workspace.issue_number}")
+
+        # Fetch issue data
+        issue_data = self.issue_fetcher.get_issue_data_dict(issue_number)
+
+        # Create workspace
+        workspace = self.workspace_manager.create_workspace(issue_data)
+        return WorkspaceInfo(WorkspaceStatus.ACTIVE, workspace)
+
+    def finish_current_workspace(self) -> Optional[int]:
+        """Finish current workspace and return the issue number.
+
+        Returns:
+            Issue number that was finished, or None if no active workspace
+
+        Raises:
+            TddaiError: If workspace operations fail
+        """
+        current_info = self.get_workspace_info()
+        if not current_info.is_active:
+            return None
+
+        issue_number = current_info.workspace.issue_number
+        self.workspace_manager.finish_workspace()
+        return issue_number
+
+    def get_workspace_summary(self) -> Dict[str, Any]:
+        """Get workspace summary for display purposes."""
+        info = self.get_workspace_info()
+
+        summary = {
+            'status': info.status,
+            'active': info.is_active,
+            'clean': info.is_clean,
+            'dirty': info.is_dirty
+        }
+
+        if info.workspace:
+            test_files = info.get_test_files()
+            summary.update({
+                'issue_number': info.workspace.issue_number,
+                'issue_title': info.workspace.issue_title,
+                'issue_state': info.workspace.issue_state,
+                'workspace_dir': str(info.workspace.workspace_dir),
+                'test_count': len(test_files),
+                'test_files': [f.name for f in test_files],
+                'requirements_file': str(info.workspace.requirements_file),
+                'test_plan_file': str(info.workspace.test_plan_file)
+            })
+
+        return summary