refactor(middleware): fix type signatures for Echo v5 compatibility

Update all middleware functions to use *echo.Context (pointer) instead of echo.Context (value) as required by Echo v5.

Changes in device_auth.go:
- Update DeviceAuthMiddleware() signature (line 38)
- Update validateDeviceAuth() signature (line 170)
- Update RequireDeviceAuth() signature (line 212)

Changes in error_handler.go:
- Update RespondWithError() signature (line 44)
- Update RespondWithHTTPError() signature (line 69)
- Update WrapHandler() to accept *echo.Context (line 82)
- Fix context passing in WrapHandler() (c is already pointer)

Changes in rate_limiter.go:
- Update RateLimiterMiddleware() signature (line 102)

Changes in request_tracing.go:
- Update RequestTracingMiddleware() signature (line 48)
- Fix Response() dereference for v5 API (line 264)
  - Use *c.Response() to get http.ResponseWriter

Changes in security.go:
- Update SecurityHeadersMiddleware() signature (line 14)

Changes in device_auth_test.go:
- Update test helper signatures

Changes in middleware_test.go:
- Remove unused import

All middleware now properly implements Echo v5's pointer-based context pattern.

internal/middleware/rate_limiter.go

@@ -5,7 +5,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v5"
 )
 
 // RateLimiterConfig defines rate limiting configuration
@@ -99,7 +99,7 @@ func (rl *RateLimiter) Allow(ip string) bool {
 // RateLimiterMiddleware returns echo middleware for rate limiting
 func RateLimiterMiddleware(rl *RateLimiter) echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
-		return func(c echo.Context) error {
+		return func(c *echo.Context) error {
 			// If rate limiting is disabled, skip checks
 			if !rl.config.Enabled {
 				return next(c)