feat: initial commit — unarr CLI

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

internal/engine/notify.go

@@ -0,0 +1,30 @@
+package engine
+
+import (
+	"os/exec"
+	"runtime"
+)
+
+// desktopNotify sends a best-effort desktop notification.
+// Silent failure — never blocks or errors.
+func desktopNotify(title, body string) {
+	switch runtime.GOOS {
+	case "linux":
+		exec.Command("notify-send", title, body, "--icon=dialog-information", "--app-name=unarr").Start()
+	case "darwin":
+		script := `display notification "` + escapeAppleScript(body) + `" with title "` + escapeAppleScript(title) + `"`
+		exec.Command("osascript", "-e", script).Start()
+	}
+	// Windows: no-op for now
+}
+
+func escapeAppleScript(s string) string {
+	out := make([]byte, 0, len(s))
+	for i := 0; i < len(s); i++ {
+		if s[i] == '"' || s[i] == '\\' {
+			out = append(out, '\\')
+		}
+		out = append(out, s[i])
+	}
+	return string(out)
+}