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/cli/__init__.py

@@ -0,0 +1,20 @@
+"""
+Command Line Interface for Universal Issue Tracking
+
+Provides a comprehensive CLI for managing issues across different backends.
+The CLI is designed to be intuitive and follows common patterns from
+tools like git, gh (GitHub CLI), and similar utilities.
+
+Commands:
+- issue list: List issues
+- issue show: Show issue details
+- issue create: Create new issue
+- issue edit: Edit existing issue
+- issue close: Close issue
+- issue reopen: Reopen issue
+- issue comment: Add comment
+- issue label: Manage labels
+- issue assign: Manage assignments
+- backend: Manage backends
+- sync: Synchronization operations
+"""