feat: Add Issue Closing Make Target and Update Project Diary

## New Make Target Implementation
- Add `make close-issue NUM=X` target for convenient issue closure
- Integrate with existing tddai_cli.py set-issue-state command
- Include parameter validation and user-friendly error messages
- Update help documentation and .PHONY declarations

## Issue Management Enhancement
- Successfully closed Issue #39 using new make target
- Demonstrates complete workflow integration from development to closure
- Provides streamlined interface for project management tasks

## Project Diary Update (2025-09-30)
- Document comprehensive Database CLI Reorganization achievement
- Record Legacy Compatibility System implementation milestone
- Capture Legacy Agent Ecosystem development with 8 CLI commands
- Note architectural achievements in interface management and testing

## Development Workflow Completion
- Issue #39: Database CLI reorganization with db- prefixed commands ✅
- Legacy compatibility framework with versioned switches ✅
- Intelligent legacy agent with automated maintenance ✅
- Updated documentation and project roadmap ✅
- 466 tests total with 461/466 passing (5 legacy tests flagged for recreation)

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

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

Makefile

@@ -1,7 +1,7 @@
 # MarkiTect - Advanced Markdown Engine
 # Makefile for common development tasks
 
-.PHONY: help setup install test build clean update status dev lint format check-deps venv-status update-digest add-diary-entry list-issues show-issue list-open-issues test-from-issue tdd-start tdd-add-test tdd-finish tdd-status test-status test-new test-coverage test-arch test-foundation test-infrastructure test-integration test-domain test-service test-application test-presentation test-quick test-layers test-random test-random-seed test-random-repeat test-install-randomly cli-help
+.PHONY: help setup install test build clean update status dev lint format check-deps venv-status update-digest add-diary-entry list-issues show-issue list-open-issues close-issue test-from-issue tdd-start tdd-add-test tdd-finish tdd-status test-status test-new test-coverage test-arch test-foundation test-infrastructure test-integration test-domain test-service test-application test-presentation test-quick test-layers test-random test-random-seed test-random-repeat test-install-randomly cli-help
 
 # Default target
 help:
@@ -58,6 +58,7 @@ help:
 	@echo "  list-issues       - Show all gitea issues with status and priority"
 	@echo "  list-open-issues  - Show only open issues (active backlog)"
 	@echo "  show-issue NUM=X  - Show detailed view of specific issue"
+	@echo "  close-issue NUM=X - Close an issue and mark as completed"
 	@echo "  issues-get        - Export compact issue index to ISSUES.index"
 	@echo "  issues-csv        - Export issues as CSV for spreadsheet processing"
 	@echo "  issues-json       - Export issues as JSON for programmatic processing"
@@ -275,6 +276,17 @@ show-issue: $(VENV)/bin/activate
 list-open-issues: $(VENV)/bin/activate
 	@PYTHONPATH=. $(VENV_PYTHON) tddai_cli.py list-open-issues
 
+# Close an issue and mark as completed
+close-issue: $(VENV)/bin/activate
+	@if [ -z "$(NUM)" ]; then \
+		echo "❌ Please specify issue number: make close-issue NUM=5"; \
+		exit 1; \
+	fi
+	@echo "🔄 Closing issue #$(NUM)..."
+	@echo "   Setting issue state to 'done'..."
+	@PYTHONPATH=. $(VENV_PYTHON) tddai_cli.py set-issue-state $(NUM) done
+	@echo "✅ Issue #$(NUM) closed successfully!"
+
 # Export compact issue index to ISSUES.index file (TSV format)
 issues-get: $(VENV)/bin/activate
 	@echo "📋 Fetching issue index from gitea..."