fix: use XDG_CONFIG_HOME for session and config files

Move default session index from proton/sessions.db (relative to CWD)
to $XDG_CONFIG_HOME/proton-cli/sessions.db (defaults to
~/.config/proton-cli/sessions.db). Same for config.yaml.

Add cmd/xdg.go with xdgConfigPath helper that respects XDG_CONFIG_HOME
and falls back to ~/.config/.

Author: major0

cmd/rootCmd.go

@@ -59,11 +59,11 @@ var (
 			}
 
 			if rootParams.ConfigFile == "" {
-				rootParams.ConfigFile = "proton/config.yaml"
+				rootParams.ConfigFile = xdgConfigPath("config.yaml")
 			}
 
 			if rootParams.SessionFile == "" {
-				rootParams.SessionFile = "proton/sessions.db"
+				rootParams.SessionFile = xdgConfigPath("sessions.db")
 			}
 
 			Timeout = rootParams.Timeout

cmd/xdg.go

@@ -0,0 +1,23 @@
+package cli
+
+import (
+	"os"
+	"path/filepath"
+)
+
+const appName = "proton-cli"
+
+// xdgConfigPath returns a path under $XDG_CONFIG_HOME/proton-cli/.
+// Defaults to ~/.config/proton-cli/ if XDG_CONFIG_HOME is unset.
+func xdgConfigPath(name string) string {
+	base := os.Getenv("XDG_CONFIG_HOME")
+	if base == "" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			// Last resort: use current directory.
+			return filepath.Join(appName, name)
+		}
+		base = filepath.Join(home, ".config")
+	}
+	return filepath.Join(base, appName, name)
+}