fix: resolve issue-facade ID mapping bugs and enhance functionality

- Fix Sentinel bug in list command where Click set search params to Sentinel.UNSET
- Fix version command by adding explicit version and package_name parameters
- Fix test isolation by correcting mock patch targets and datetime objects
- Fix critical ID mapping bug: use issue.number consistently instead of mixing with issue.backend_id
- Update all comment operations to use issue numbers instead of internal IDs
- Ensure issue-facade uses upstream issue numbers directly without local ID confusion
- Add comprehensive test coverage with 20 passing tests
- Verify core functionality: list, show, close, version, backend management all working
- Successfully close issue #166 with proper comment handling

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

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

issue_tracker/__init__.py

@@ -0,0 +1,24 @@
+"""
+Universal Issue Tracking System
+
+A backend-agnostic issue tracking system that supports multiple backends
+through a plugin architecture. Designed to be extracted into a standalone
+repository for use across multiple projects.
+
+Features:
+- Unified issue model across all backends
+- Plugin-based backend architecture
+- Local SQLite backend for offline work
+- Bidirectional synchronization
+- CLI-first interface
+- Support for GitHub-style and other issue tracking systems
+
+Supported Backends:
+- Local SQLite (for offline/standalone use)
+- Gitea (GitHub-compatible API)
+- Future: GitHub, GitLab, JIRA, Redmine, etc.
+"""
+
+__version__ = "0.1.0"
+__author__ = "MarkiTect Project"
+__description__ = "Universal Issue Tracking System with Plugin Architecture"