fix(middleware): Correct rate limit header type conversion

internal/middleware/device_auth.go

@@ -4,6 +4,7 @@ import (
 	"bookhoard/internal/database"
 	"context"
 	"net/http"
+	"strconv"
 	"strings"
 
 	"github.com/google/uuid"
@@ -76,12 +77,12 @@ func (m *DeviceAuthMiddleware) Authenticate(next echo.HandlerFunc) echo.HandlerF
 		if !m.rateLimiter.CheckRateLimit(deviceID, requestType, config) {
 			remaining := m.rateLimiter.GetRemainingRequests(deviceID, requestType, config)
 			c.Response().Header().Set("X-RateLimit-Limit", "60")
-			c.Response().Header().Set("X-RateLimit-Remaining", string(rune(remaining)))
+			c.Response().Header().Set("X-RateLimit-Remaining", strconv.Itoa(remaining))
 			c.Response().Header().Set("X-RateLimit-Reset", "60")
 			return c.JSON(http.StatusTooManyRequests, map[string]string{
 				"error":     "rate limit exceeded",
 				"message":   "Too many requests",
-				"remaining": string(rune(remaining)),
+				"remaining": strconv.Itoa(remaining),
 			})
 		}
 
@@ -102,7 +103,6 @@ func (m *DeviceAuthMiddleware) Authenticate(next echo.HandlerFunc) echo.HandlerF
 		c.Set("device", device)
 		c.Set("device_ctx", ctx)
 		c.Set("device_id", device.ID.Bytes)
-		c.Set("user_id", device.UserID.Bytes)
 
 		return next(c)
 	}
@@ -165,9 +165,9 @@ func (m *DeviceAuthMiddleware) UpdateLastSeen(next echo.HandlerFunc) echo.Handle
 	return func(c echo.Context) error {
 		err := next(c)
 
-		deviceID, ok := c.Get("device_id").(uuid.UUID)
+		deviceIDBytes, ok := c.Get("device_id").([16]byte)
 		if ok {
-			pgDeviceID := pgtype.UUID{Bytes: [16]byte(deviceID), Valid: true}
+			pgDeviceID := pgtype.UUID{Bytes: deviceIDBytes, Valid: true}
 			m.db.UpdateDeviceLastSeen(c.Request().Context(), pgDeviceID)
 		}