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/issue_service.py

@@ -0,0 +1,69 @@
+"""
+Issue service - business logic for issue operations.
+"""
+
+from typing import List, Dict, Any, Optional
+from datetime import datetime
+
+from tddai import IssueFetcher, TddaiError
+from tddai.issue_creator import IssueCreator
+from gitea.models import Issue, Priority
+
+
+class IssueService:
+    """Service for issue operations."""
+
+    def __init__(self):
+        self.issue_fetcher = IssueFetcher()
+        self.issue_creator = IssueCreator()
+
+    def get_issue(self, issue_number: int) -> Issue:
+        """Get a specific issue by number."""
+        return self.issue_fetcher.fetch_issue(issue_number)
+
+    def list_issues(self, state: str = "all") -> List[Issue]:
+        """List issues with optional state filter."""
+        return self.issue_fetcher.fetch_issues(state)
+
+    def list_open_issues(self) -> List[Issue]:
+        """List only open issues."""
+        return self.issue_fetcher.fetch_open_issues()
+
+    def create_issue(self, title: str, body: str, **kwargs) -> Dict[str, Any]:
+        """Create a new issue."""
+        return self.issue_creator.create_issue(title, body, **kwargs)
+
+    def create_enhancement_issue(self, title: str, use_case: str,
+                               technical_requirements: str = "",
+                               acceptance_criteria: List[str] = None,
+                               dependencies: List[str] = None,
+                               priority: str = "Medium") -> Dict[str, Any]:
+        """Create a structured enhancement issue."""
+        return self.issue_creator.create_enhancement_issue(
+            title, use_case, technical_requirements,
+            acceptance_criteria, dependencies, priority
+        )
+
+    def create_from_template(self, template_file: str, **kwargs) -> Dict[str, Any]:
+        """Create issue from template file."""
+        return self.issue_creator.create_from_template(template_file, **kwargs)
+
+    def get_issue_summary(self, issue_number: int) -> Dict[str, Any]:
+        """Get issue summary for display purposes."""
+        issue = self.get_issue(issue_number)
+
+        return {
+            'number': issue.number,
+            'title': issue.title,
+            'body': issue.body,
+            'state': issue.state,
+            'priority': issue.priority,
+            'status': issue.status,
+            'created_at': issue.created_at,
+            'updated_at': issue.updated_at,
+            'html_url': issue.html_url,
+            'assignee': issue.assignee.login if issue.assignee else None,
+            'labels': [label.name for label in issue.labels],
+            'has_milestone': issue.milestone is not None,
+            'milestone_title': issue.milestone.title if issue.milestone else None
+        }