fix(notifications): bring back legacy notification handling (#9015)

# Which Problems Are Solved

There are some problems related to the use of CockroachDB with the new
notification handling (#8931).
See #9002 for details.

# How the Problems Are Solved

- Brought back the previous notification handler as legacy mode.
- Added a configuration to choose between legacy mode and new parallel
workers.
  - Enabled legacy mode by default to prevent issues.

# Additional Changes

None

# Additional Context

- closes https://github.com/zitadel/zitadel/issues/9002
- relates to #8931

internal/api/ui/login/init_password_handler.go

@@ -3,6 +3,7 @@ package login
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 
 	http_mw "github.com/zitadel/zitadel/internal/api/http/middleware"
 	"github.com/zitadel/zitadel/internal/domain"
@@ -38,6 +39,15 @@ type initPasswordData struct {
 	HasSymbol    string
 }
 
+func InitPasswordLink(origin, userID, code, orgID, authRequestID string) string {
+	v := url.Values{}
+	v.Set(queryInitPWUserID, userID)
+	v.Set(queryInitPWCode, code)
+	v.Set(queryOrgID, orgID)
+	v.Set(QueryAuthRequestID, authRequestID)
+	return externalLink(origin) + EndpointInitPassword + "?" + v.Encode()
+}
+
 func InitPasswordLinkTemplate(origin, userID, orgID, authRequestID string) string {
 	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%s&%s=%s",
 		externalLink(origin), EndpointInitPassword,

internal/api/ui/login/init_user_handler.go

@@ -3,6 +3,7 @@ package login
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 	"strconv"
 
 	http_mw "github.com/zitadel/zitadel/internal/api/http/middleware"
@@ -44,6 +45,17 @@ type initUserData struct {
 	HasSymbol    string
 }
 
+func InitUserLink(origin, userID, loginName, code, orgID string, passwordSet bool, authRequestID string) string {
+	v := url.Values{}
+	v.Set(queryInitUserUserID, userID)
+	v.Set(queryInitUserLoginName, loginName)
+	v.Set(queryInitUserCode, code)
+	v.Set(queryOrgID, orgID)
+	v.Set(queryInitUserPassword, strconv.FormatBool(passwordSet))
+	v.Set(QueryAuthRequestID, authRequestID)
+	return externalLink(origin) + EndpointInitUser + "?" + v.Encode()
+}
+
 func InitUserLinkTemplate(origin, userID, orgID, authRequestID string) string {
 	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%s&%s=%s&%s=%s&%s=%s",
 		externalLink(origin), EndpointInitUser,

internal/api/ui/login/invite_user_handler.go

@@ -3,6 +3,7 @@ package login
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 
 	http_mw "github.com/zitadel/zitadel/internal/api/http/middleware"
 	"github.com/zitadel/zitadel/internal/domain"
@@ -40,6 +41,16 @@ type inviteUserData struct {
 	HasSymbol    string
 }
 
+func InviteUserLink(origin, userID, loginName, code, orgID string, authRequestID string) string {
+	v := url.Values{}
+	v.Set(queryInviteUserUserID, userID)
+	v.Set(queryInviteUserLoginName, loginName)
+	v.Set(queryInviteUserCode, code)
+	v.Set(queryOrgID, orgID)
+	v.Set(QueryAuthRequestID, authRequestID)
+	return externalLink(origin) + EndpointInviteUser + "?" + v.Encode()
+}
+
 func InviteUserLinkTemplate(origin, userID, orgID string, authRequestID string) string {
 	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%s&%s=%s&%s=%s",
 		externalLink(origin), EndpointInviteUser,

internal/api/ui/login/mail_verify_handler.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"net/url"
 	"slices"
 
 	"github.com/zitadel/logging"
@@ -43,6 +44,15 @@ type mailVerificationData struct {
 	HasSymbol    string
 }
 
+func MailVerificationLink(origin, userID, code, orgID, authRequestID string) string {
+	v := url.Values{}
+	v.Set(queryUserID, userID)
+	v.Set(queryCode, code)
+	v.Set(queryOrgID, orgID)
+	v.Set(QueryAuthRequestID, authRequestID)
+	return externalLink(origin) + EndpointMailVerification + "?" + v.Encode()
+}
+
 func MailVerificationLinkTemplate(origin, userID, orgID, authRequestID string) string {
 	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%s&%s=%s",
 		externalLink(origin), EndpointMailVerification,

internal/api/ui/login/mfa_verify_otp_handler.go

@@ -27,6 +27,10 @@ type mfaOTPFormData struct {
 	Provider         domain.MFAType `schema:"provider"`
 }
 
+func OTPLink(origin, authRequestID, code string, provider domain.MFAType) string {
+	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%d", externalLink(origin), EndpointMFAOTPVerify, QueryAuthRequestID, authRequestID, queryCode, code, querySelectedProvider, provider)
+}
+
 func OTPLinkTemplate(origin, authRequestID string, provider domain.MFAType) string {
 	return fmt.Sprintf("%s%s?%s=%s&%s=%s&%s=%d", externalLink(origin), EndpointMFAOTPVerify, QueryAuthRequestID, authRequestID, queryCode, "{{.Code}}", querySelectedProvider, provider)
 }