feat: initial commit — unarr CLI

Search, inspect, stream, and download torrents from the terminal.
Replaces the entire *arr stack with a single binary.

internal/agent/disk_unix.go

@@ -0,0 +1,17 @@
+//go:build !windows
+
+package agent
+
+import "syscall"
+
+// DiskInfo returns free and total bytes for the filesystem containing path.
+func DiskInfo(path string) (freeBytes, totalBytes int64, err error) {
+	var stat syscall.Statfs_t
+	if err := syscall.Statfs(path, &stat); err != nil {
+		return 0, 0, err
+	}
+	// Available blocks * block size
+	freeBytes = int64(stat.Bavail) * int64(stat.Bsize)
+	totalBytes = int64(stat.Blocks) * int64(stat.Bsize)
+	return freeBytes, totalBytes, nil
+}