Add webhook logging, pagination, middleware, migrations, and prod hardening

- Webhook event logging repo and subscription webhook idempotency
- Pagination helper (echohelpers) with cursor/offset support
- Request ID and structured logging middleware
- Push client improvements (FCM HTTP v1, better error handling)
- Task model version column, business constraint migrations, targeted indexes
- Expanded categorization chain tests
- Email service and config hardening
- CI workflow updates, .gitignore additions, .env.example updates

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

internal/services/email_service.go

@@ -15,22 +15,28 @@ import (
 
 // EmailService handles sending emails
 type EmailService struct {
-	cfg    *config.EmailConfig
-	dialer *gomail.Dialer
+	cfg     *config.EmailConfig
+	dialer  *gomail.Dialer
+	enabled bool
 }
 
 // NewEmailService creates a new email service
-func NewEmailService(cfg *config.EmailConfig) *EmailService {
+func NewEmailService(cfg *config.EmailConfig, enabled bool) *EmailService {
 	dialer := gomail.NewDialer(cfg.Host, cfg.Port, cfg.User, cfg.Password)
 
 	return &EmailService{
-		cfg:    cfg,
-		dialer: dialer,
+		cfg:     cfg,
+		dialer:  dialer,
+		enabled: enabled,
 	}
 }
 
 // SendEmail sends an email
 func (s *EmailService) SendEmail(to, subject, htmlBody, textBody string) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)
@@ -64,6 +70,10 @@ type EmbeddedImage struct {
 
 // SendEmailWithAttachment sends an email with an attachment
 func (s *EmailService) SendEmailWithAttachment(to, subject, htmlBody, textBody string, attachment *EmailAttachment) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)
@@ -94,6 +104,10 @@ func (s *EmailService) SendEmailWithAttachment(to, subject, htmlBody, textBody s
 
 // SendEmailWithEmbeddedImages sends an email with inline embedded images
 func (s *EmailService) SendEmailWithEmbeddedImages(to, subject, htmlBody, textBody string, images []EmbeddedImage) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)