Implement Issue #1: User Accounts & Profiles

- Admin-only account creation (no self-registration); invite-token flow
  replaces the public /auth/register endpoint
- New volunteer fields: phone, is_trainee, operational_roles,
  notification_preference, admin_notes, last_login, completed_shifts
- Role-scoped profile editing: volunteers update name/phone only;
  admins update all fields including notes and trainee flag
- /auth/activate endpoint for invite-token-based account activation
- /api/v1/volunteers/{id}/invite for admin to resend invite links
- last_login recorded on each successful authentication

Tests:
- Go: handler tests (auth rules, create, activate, update scoping) via
  Storer/AuthServicer interfaces and fake store; auth unit tests for
  HashPassword, IssueToken, and Parse
- Frontend: RTL tests for Activate, Profile, and Volunteers pages
- Fixed CRA 5 + React Router v7 Jest compatibility (moduleNameMapper +
  TextEncoder polyfill)
- Replaced stale CRA App.test.tsx placeholder with real tests

CI:
- .gitea/workflows/ci.yml runs go vet, go test, tsc, and npm test on
  every push and pull request

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/auth/auth.go

@@ -28,23 +28,25 @@ func NewService(db *sql.DB, secret string) *Service {
 	return &Service{db: db, jwtSecret: []byte(secret)}
 }
 
-func (s *Service) Login(ctx context.Context, email, password string) (string, error) {
+// Login authenticates by email/password and returns the volunteer ID and JWT token.
+func (s *Service) Login(ctx context.Context, email, password string) (int64, string, error) {
 	var id int64
 	var hash, role string
 	err := s.db.QueryRowContext(ctx,
-		`SELECT id, password, role FROM volunteers WHERE email = ? AND active = 1`,
+		`SELECT id, password, role FROM volunteers WHERE email = ? AND active = 1 AND (password != '' AND password IS NOT NULL)`,
 		email,
 	).Scan(&id, &hash, &role)
 	if errors.Is(err, sql.ErrNoRows) {
-		return "", ErrInvalidCredentials
+		return 0, "", ErrInvalidCredentials
 	}
 	if err != nil {
-		return "", fmt.Errorf("query volunteer: %w", err)
+		return 0, "", fmt.Errorf("query volunteer: %w", err)
 	}
 	if err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password)); err != nil {
-		return "", ErrInvalidCredentials
+		return 0, "", ErrInvalidCredentials
 	}
-	return s.issueToken(id, role)
+	token, err := s.issueToken(id, role)
+	return id, token, err
 }
 
 func (s *Service) issueToken(volunteerID int64, role string) (string, error) {
@@ -81,3 +83,9 @@ func HashPassword(password string) (string, error) {
 	b, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
 	return string(b), err
 }
+
+// IssueToken mints a JWT for the given volunteer ID and role without querying the DB.
+// Intended for use in tests and invite-activation flows.
+func (s *Service) IssueToken(volunteerID int64, role string) (string, error) {
+	return s.issueToken(volunteerID, role)
+}