refactor(drivers): organize backup modules into drivers subfolder

- Move all backup_*.py files to libtisbackup/drivers/ subdirectory
- Move XenAPI.py and copy_vm_xcp.py to drivers/ (driver-specific)
- Create drivers/__init__.py with automatic driver imports
- Update tisbackup.py imports to use new structure
- Add pyvmomi>=8.0.0 as mandatory dependency
- Sync requirements.txt with pyproject.toml dependencies
- Add pylint>=3.0.0 and pytest-cov>=6.0.0 to dev dependencies
- Configure pylint and coverage tools in pyproject.toml
- Add conventional commits guidelines to CLAUDE.md
- Enhance .gitignore with comprehensive patterns for Python, IDEs, testing, and secrets
- Update CLAUDE.md documentation with new structure and tooling

Breaking Changes:
- Drivers must now be imported from libtisbackup.drivers instead of libtisbackup
- All backup driver files relocated to drivers/ subdirectory

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

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

tisbackup.py

@@ -34,23 +34,9 @@ from optparse import OptionParser
 
 from iniparse import ConfigParser, ini
 
-from libtisbackup.backup_mysql import backup_mysql
-
-# from libtisbackup.backup_vmdk import backup_vmdk
-# from libtisbackup.backup_switch import backup_switch
-from libtisbackup.backup_null import backup_null
-from libtisbackup.backup_pgsql import backup_pgsql
-from libtisbackup.backup_rsync import backup_rsync, backup_rsync_ssh
-
-# from libtisbackup.backup_oracle import backup_oracle
-from libtisbackup.backup_rsync_btrfs import backup_rsync__btrfs_ssh, backup_rsync_btrfs
-
-# from libtisbackup.backup_sqlserver import backup_sqlserver
-from libtisbackup.backup_samba4 import backup_samba4
-from libtisbackup.backup_xcp_metadata import backup_xcp_metadata
-from libtisbackup.backup_xva import backup_xva
-from libtisbackup.common import *
-from libtisbackup.copy_vm_xcp import copy_vm_xcp
+# Import all backup drivers - this registers them with the driver registry
+from libtisbackup.drivers import *
+from libtisbackup import *
 
 __version__ = "2.0"