refactor: simplify config into a single load/save with defaults resolved at load time

src/store/session.go

@@ -13,6 +13,8 @@ type Session struct {
 	Token string `json:"token"`
 }
 
+// LoadSession reads the session token from disk. If no session file
+// exists, an empty Session is returned (Token will be "").
 func LoadSession() (*Session, error) {
 	sessionRoot, err := FindDataRoot(".local", "share")
 	if err != nil {
@@ -34,6 +36,7 @@ func LoadSession() (*Session, error) {
 	return &s, nil
 }
 
+// Save writes the session token to disk with restrictive permissions (0600).
 func (s *Session) Save() error {
 	if err := os.MkdirAll(filepath.Dir(s.path), 0700); err != nil {
 		return err
@@ -45,6 +48,7 @@ func (s *Session) Save() error {
 	return os.WriteFile(s.path, data, 0600)
 }
 
+// ClearSession deletes the session file from disk.
 func (s *Session) ClearSession() error {
 	err := os.Remove(s.path)
 	if os.IsNotExist(err) {