fix(backend): dbErr 503 degradation for connection-class DB errors

backend/internal/api/users.go

@@ -2,7 +2,6 @@ package api
 
 import (
 	"errors"
-	"log"
 	"net/http"
 	"strconv"
 	"time"
@@ -22,8 +21,7 @@ func isUnique(e error) bool {
 func (a *api) listUsers(c *gin.Context) {
 	users, e := a.st.ListUsers(c)
 	if e != nil {
-		log.Printf("db: %v", e)
-		err(c, http.StatusInternalServerError, "internal", "db error")
+		dbErr(c, e)
 		return
 	}
 	out := make([]gin.H, 0, len(users))
@@ -59,7 +57,7 @@ func (a *api) createUser(c *gin.Context) {
 			err(c, http.StatusConflict, "exists", "username taken")
 			return
 		}
-		err(c, http.StatusBadRequest, "bad_request", "invalid input")
+		dbErr(c, e)
 		return
 	}
 	c.JSON(http.StatusCreated, gin.H{"id": id, "username": req.Username, "role": req.Role})
@@ -81,7 +79,7 @@ func (a *api) deleteUser(c *gin.Context) {
 			err(c, http.StatusNotFound, "not_found", "no such user")
 			return
 		}
-		err(c, http.StatusInternalServerError, "internal", "db error")
+		dbErr(c, e)
 		return
 	}
 	if target.Role == "admin" {
@@ -92,7 +90,7 @@ func (a *api) deleteUser(c *gin.Context) {
 		}
 	}
 	if e := a.st.DeleteUser(c, id); e != nil {
-		err(c, http.StatusInternalServerError, "internal", "db error")
+		dbErr(c, e)
 		return
 	}
 	c.Status(http.StatusNoContent)