feat(backend): update webhooks and DAV service

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/internal/dav/service_dev.go

@@ -26,7 +26,7 @@ func init() {
 
 func connect() error {
 	dsn := fmt.Sprintf(
-		"postgres://%s:%s@localhost:5432/%s?sslmode=disable",
+		"postgres://%s:%s@localhost:5432/%s?sslmode=disable&require_auth=scram-sha-256",
 		getEnv("POSTGRES_USER"),
 		getEnv("POSTGRES_PASSWORD"),
 		getEnv("POSTGRES_DB"),

backend/internal/dav/service_prod.go

@@ -26,7 +26,7 @@ func init() {
 
 func connect() error {
 	dsn := fmt.Sprintf(
-		"postgres://%s:%s@%s:5432/%s",
+		"postgres://%s:%s@%s:5432/%s?require_auth=scram-sha-256",
 		getEnv("POSTGRES_USER"),
 		getEnv("POSTGRES_PASSWORD"),
 		getEnv("POSTGRES_HOST"),