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>

libtisbackup/drivers/__init__.py

@@ -0,0 +1,60 @@
+# -----------------------------------------------------------------------
+#    This file is part of TISBackup
+#
+#    TISBackup is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    TISBackup is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with TISBackup.  If not, see <http://www.gnu.org/licenses/>.
+#
+# -----------------------------------------------------------------------
+
+"""
+TISBackup drivers - Pluggable backup driver implementations.
+
+This package contains all backup driver implementations:
+- Database drivers (MySQL, PostgreSQL, Oracle, SQL Server)
+- File sync drivers (rsync, rsync+btrfs)
+- VM backup drivers (XenServer XVA, VMware VMDK)
+- Other drivers (Samba4, network switches, etc.)
+"""
+
+# Import all drivers to ensure they register themselves
+from .backup_mysql import backup_mysql
+from .backup_null import backup_null
+from .backup_oracle import backup_oracle
+from .backup_pgsql import backup_pgsql
+from .backup_rsync import backup_rsync, backup_rsync_ssh
+from .backup_rsync_btrfs import backup_rsync_btrfs, backup_rsync__btrfs_ssh
+from .backup_samba4 import backup_samba4
+from .backup_sqlserver import backup_sqlserver
+from .backup_switch import backup_switch
+from .backup_vmdk import backup_vmdk
+from .backup_xcp_metadata import backup_xcp_metadata
+from .backup_xva import backup_xva
+from .copy_vm_xcp import copy_vm_xcp
+
+__all__ = [
+    "backup_mysql",
+    "backup_null",
+    "backup_oracle",
+    "backup_pgsql",
+    "backup_rsync",
+    "backup_rsync_ssh",
+    "backup_rsync_btrfs",
+    "backup_rsync__btrfs_ssh",
+    "backup_samba4",
+    "backup_sqlserver",
+    "backup_switch",
+    "backup_vmdk",
+    "backup_xcp_metadata",
+    "backup_xva",
+    "copy_vm_xcp",
+]