test: add comprehensive tests for notes and highlights

- Add complete test suite for media notes API with validation
- Add complete test suite for media highlights API with color validation
- Add backward compatibility tests for ebook endpoints
- Test authentication scenarios (unauthorized access)
- Test request validation and error handling
- Fix existing test import issues and syntax errors
- Add test cases for highlight-note associations

cmd/server/tests/auth_test.go

@@ -1,14 +1,15 @@
 package main
 
 import (
-	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
-func TestAuthMiddleware(t *testing.T) {
+func TestAuthMiddlewareAlt(t *testing.T) {
 	// Test missing JWT header
 	t.Run("Missing JWT", func(t *testing.T) {
 		req := httptest.NewRequest("GET", "/api/libraries/visible", nil)