Implement JWT authentication and app passkey support

- Add JWT token generation and validation
- Implement bcrypt password hashing
- Create auth service with register/login/refresh/logout
- Add app passkey generation and management
- Implement protected routes and auth middleware
- Add comprehensive tests for new functionality

internal/auth/jwt_test.go

@@ -0,0 +1,93 @@
+package auth
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestGenerateAccessToken(t *testing.T) {
+	secret := []byte("test-secret")
+	token, err := GenerateAccessToken("user-1", secret, 15*time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateAccessToken = %v", err)
+	}
+	if token == "" {
+		t.Fatal("token is empty")
+	}
+	if !strings.Contains(token, ".") {
+		t.Fatal("token does not look like a JWT")
+	}
+}
+
+func TestParseTokenValid(t *testing.T) {
+	secret := []byte("test-secret")
+	token, err := GenerateAccessToken("user-1", secret, 15*time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateAccessToken = %v", err)
+	}
+
+	claims, err := ParseToken(token, secret)
+	if err != nil {
+		t.Fatalf("ParseToken = %v", err)
+	}
+	if claims.UserID != "user-1" {
+		t.Errorf("UserID = %q, want %q", claims.UserID, "user-1")
+	}
+}
+
+func TestParseTokenWrongSecret(t *testing.T) {
+	secret := []byte("test-secret")
+	token, err := GenerateAccessToken("user-1", secret, 15*time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateAccessToken = %v", err)
+	}
+
+	_, err = ParseToken(token, []byte("wrong-secret"))
+	if err == nil {
+		t.Fatal("expected error for wrong secret, got nil")
+	}
+}
+
+func TestParseTokenExpired(t *testing.T) {
+	secret := []byte("test-secret")
+	token, err := GenerateAccessToken("user-1", secret, -1*time.Minute)
+	if err != nil {
+		t.Fatalf("GenerateAccessToken = %v", err)
+	}
+
+	_, err = ParseToken(token, secret)
+	if err == nil {
+		t.Fatal("expected error for expired token, got nil")
+	}
+}
+
+func TestParseTokenInvalidFormat(t *testing.T) {
+	_, err := ParseToken("not-a-jwt", []byte("secret"))
+	if err == nil {
+		t.Fatal("expected error for invalid format, got nil")
+	}
+}
+
+func TestGenerateRefreshToken(t *testing.T) {
+	secret := []byte("test-secret")
+	token, err := GenerateRefreshToken("user-1", secret, 7*24*time.Hour)
+	if err != nil {
+		t.Fatalf("GenerateRefreshToken = %v", err)
+	}
+	if token == "" {
+		t.Fatal("token is empty")
+	}
+}
+
+func TestTokenUserIDCarried(t *testing.T) {
+	secret := []byte("test-secret")
+	token, _ := GenerateAccessToken("alice-42", secret, 15*time.Minute)
+	claims, err := ParseToken(token, secret)
+	if err != nil {
+		t.Fatalf("ParseToken = %v", err)
+	}
+	if claims.UserID != "alice-42" {
+		t.Errorf("UserID = %q, want %q", claims.UserID, "alice-42")
+	}
+}