feat: x3-backup v1.0.0 initial release

GTK3 backup/snapshot tool using rsync backend.

Features:
- rsync-based snapshots with hardlink delta for space efficiency
- Snapshot sidebar with date-sorted list
- Full file browser with permissions display (name, size, perms, mtime)
- Right-click context menu: Restore file/dir with sudo prompt
- System tray icon: backup status, context menu (show/backup/settings/quit)
- Menu system: File, Backup, System, Help
- Settings dialog: backup destination, source path, retention, exclusions
- Cronjob management: install/remove scheduled backups
- Live Log tab: real-time rsync output during backup
- History Log tab: full log file viewer with color-coded entries
- System Backup mode: full root filesystem backup
- System Restore mode: restore entire system from snapshot
- CLI mode: --backup, --system-backup for cron/headless use
- /mnt always excluded from backups
- Preserves permissions, ACLs, xattrs (-aAX flags)
- Log file: ~/.config/x3-backup/x3-backup.log
- Config: ~/.config/x3-backup/settings.json
- uninstall.sh for clean removal

src/rsync_manager.h

@@ -0,0 +1,57 @@
+#pragma once
+#include <string>
+#include <vector>
+#include <functional>
+#include <atomic>
+#include <thread>
+#include <mutex>
+#include "config.h"
+
+struct RsyncProgress {
+	int64_t files_transferred = 0;
+	int64_t files_total = 0;
+	int64_t bytes_transferred = 0;
+	int64_t bytes_total = 0;
+	int speed = 0;
+	std::string current_file;
+	std::string log_line;
+	bool finished = false;
+	bool error = false;
+	std::string error_message;
+};
+
+class RsyncManager {
+public:
+	RsyncManager(Config& config);
+
+	bool create_snapshot(const std::string& snapshot_name,
+	                     const std::string& source,
+	                     const std::string& dest,
+	                     const std::string& link_dest = "");
+
+	bool restore_files(const std::string& snapshot_path,
+	                   const std::vector<std::string>& files,
+	                   const std::string& restore_dest,
+	                   const std::string& sudo_password);
+
+	bool restore_full_snapshot(const std::string& snapshot_path,
+	                           const std::string& restore_dest,
+	                           const std::string& sudo_password);
+
+	void cancel();
+	bool is_running() const { return running_; }
+
+	std::function<void(const RsyncProgress&)> on_progress;
+
+private:
+	Config& config_;
+	std::atomic<bool> running_{false};
+	std::atomic<bool> cancel_requested_{false};
+	std::thread worker_;
+	std::mutex log_mutex_;
+	std::vector<std::string> log_buffer_;
+
+	std::vector<std::string> build_exclude_args();
+	bool run_rsync(const std::vector<std::string>& args);
+	void parse_progress_line(const std::string& line, RsyncProgress& prog);
+};