Add CHANGELOG and update README with new features

Added:
- CHANGELOG.md following Keep a Changelog format
- Documented all changes from v1.0.0 to current unreleased version
- README section explaining reconfiguration options
- Enhanced troubleshooting section with connection test details

The CHANGELOG documents:
- Reconfiguration feature for existing installations
- Connection test timeout and improved error messages
- Installation method change from wget to git clone

The README now clearly explains:
- How to reconfigure existing installations
- Connection-only vs full reconfiguration options
- Use cases for quick connection updates
- Connection test timeout behavior and error types

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

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

CHANGELOG.md

@@ -0,0 +1,46 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Intelligent reconfiguration options when PBS client is already installed
+  - Quick connection-only reconfiguration (server/credentials only)
+  - Full reconfiguration of all settings
+  - Reinstall option with reconfiguration
+  - Exit without changes option
+- Connection test timeout (30 seconds) to prevent indefinite hanging
+- Detailed error messages for connection failures
+  - Differentiates between timeout and authentication errors
+  - Provides specific troubleshooting steps based on error type
+  - Displays helpful diagnostic commands
+
+### Changed
+- Installation instructions now use `git clone` instead of `wget`
+- Connection test provides better user feedback during testing
+- Script now detects existing configurations and offers appropriate options
+
+### Fixed
+- Script no longer hangs indefinitely when PBS server is unreachable
+- Connection test now properly handles timeout scenarios
+
+## [1.0.0] - 2025-11-01
+
+### Added
+- Initial release
+- Auto-detection of Linux distribution (Ubuntu, Debian, Arch)
+- Interactive configuration via console prompts
+- Automatic encryption key generation with paper backup
+- Systemd service and timer for automated backups
+- Configurable retention policies
+- Connection testing before finalization
+- Immediate backup option after installation
+- Support for file-level (.pxar) backups
+- Support for block device (.img) backups
+- Hybrid backup mode (daily files + weekly block device)
+- Comprehensive error handling and logging
+- Uninstaller script

README.md

@@ -47,6 +47,29 @@ chmod +x pbs-client-installer.sh
 sudo ./pbs-client-installer.sh
 ```
 
+### Reconfiguration
+
+If PBS client is already installed, the script will detect this and offer you options:
+
+**With existing configuration:**
+- **Reconfigure connection only** - Quick update of PBS server IP/credentials only
+- **Full reconfiguration** - Redo all settings (paths, schedules, retention, etc.)
+- **Reinstall PBS client and reconfigure** - Complete reinstall
+- **Exit without changes**
+
+**Without existing configuration:**
+- **Configure PBS client** - Set up for the first time
+- **Reinstall and configure** - Fresh installation
+- **Exit without changes**
+
+The connection-only reconfiguration is perfect for:
+- Switching to a different backup server
+- Updating expired API tokens
+- Changing authentication methods
+- Updating datastore names
+
+All backup settings (paths, schedules, retention policies) are preserved.
+
 ## Usage Example
 
 The script will interactively prompt you for:
@@ -232,6 +255,18 @@ sudo cp /path/to/saved/encryption-key.json /root/.config/proxmox-backup/
 
 ### Connection Test Fails
 
+The installer tests the connection with a 30-second timeout. If it fails, you'll see specific error messages:
+
+**Timeout errors** (30+ seconds):
+- PBS server is unreachable (check IP/hostname)
+- Firewall blocking port (default: 8007)
+- Network connectivity issues
+
+**Authentication errors** (immediate failure):
+- Invalid credentials (username/password/token)
+- Datastore does not exist on server
+- User lacks permissions for the datastore
+
 Check your PBS server is accessible:
 ```bash
 ping 192.168.1.181