feat(db): add memory storage driver

removes the sqlite dependency for tests, also brings back the option for
users to run zero persistence instances of tinyauth.

adds new mapErr fn for sqlc wrapper gen to prevent sql errors from
leaking out of the store implementation.

internal/repository/memory/session_queries.go

@@ -0,0 +1,63 @@
+package memory
+
+import (
+	"context"
+
+	"github.com/tinyauthapp/tinyauth/internal/repository"
+)
+
+func (s *Store) CreateSession(_ context.Context, arg repository.CreateSessionParams) (repository.Session, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	sess := repository.Session(arg)
+	s.sessions[arg.UUID] = sess
+	return sess, nil
+}
+
+func (s *Store) GetSession(_ context.Context, uuid string) (repository.Session, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	sess, ok := s.sessions[uuid]
+	if !ok {
+		return repository.Session{}, repository.ErrNotFound
+	}
+	return sess, nil
+}
+
+func (s *Store) UpdateSession(_ context.Context, arg repository.UpdateSessionParams) (repository.Session, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	sess, ok := s.sessions[arg.UUID]
+	if !ok {
+		return repository.Session{}, repository.ErrNotFound
+	}
+	sess.Username = arg.Username
+	sess.Email = arg.Email
+	sess.Name = arg.Name
+	sess.Provider = arg.Provider
+	sess.TotpPending = arg.TotpPending
+	sess.OAuthGroups = arg.OAuthGroups
+	sess.Expiry = arg.Expiry
+	sess.OAuthName = arg.OAuthName
+	sess.OAuthSub = arg.OAuthSub
+	s.sessions[arg.UUID] = sess
+	return sess, nil
+}
+
+func (s *Store) DeleteSession(_ context.Context, uuid string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.sessions, uuid)
+	return nil
+}
+
+func (s *Store) DeleteExpiredSessions(_ context.Context, expiry int64) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for k, v := range s.sessions {
+		if v.Expiry < expiry {
+			delete(s.sessions, k)
+		}
+	}
+	return nil
+}