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>

cli/commands/export.py

@@ -0,0 +1,46 @@
+"""
+Export and reporting CLI commands.
+"""
+
+import sys
+from typing import Optional
+
+from tddai import TddaiError
+from services import ExportService
+from cli.presenters import OutputFormatter
+
+
+class ExportCommands:
+    """Commands for data export and reporting."""
+
+    def __init__(self):
+        self.service = ExportService()
+
+    def issue_index(self, format_type: str = "tsv", sort_by: str = "number",
+                   filter_state: Optional[str] = None, filter_priority: Optional[str] = None,
+                   include_state: bool = False) -> None:
+        """Output compact index of all issues for Unix processing.
+
+        Args:
+            format_type: Output format (tsv, csv, json, fields)
+            sort_by: Sort by field (number, title, priority, state, created, updated)
+            filter_state: Filter by state (open, closed)
+            filter_priority: Filter by priority (low, medium, high, critical, none)
+            include_state: Include state column in output
+        """
+        try:
+            output = self.service.export_issues(
+                format_type=format_type,
+                sort_by=sort_by,
+                filter_state=filter_state,
+                filter_priority=filter_priority,
+                include_state=include_state
+            )
+
+            # Output directly to stdout for piping
+            print(output)
+
+        except TddaiError as e:
+            # Send error to stderr to avoid corrupting piped output
+            print(f"❌ Error: {e}", file=sys.stderr)
+            sys.exit(1)