refactor(tests): update test helpers and all test file references

- Rename createTestEbookID to createTestMediaItemID in test_helpers.go
- Update test helper comments and variable names (ebookReq -> mediaItemReq, etc.)
- Update all test file references:
  - analytics_test.go
  - book_matching_test.go
  - collections_bulk_test.go
  - kobo_test.go
  - media_bulk_test.go
  - opds_test.go
- Rename ebookID variable to mediaItemID in kobo_test.go
- Update test data to use 'Test Media Item' instead of 'Test Ebook'

cmd/server/tests/test_helpers.go

@@ -269,12 +269,12 @@ func getTestUserID(t *testing.T, db *database.Queries) uuid.UUID {
 	return userUUID
 }
 
-// createTestEbookID creates a test ebook and returns its ID
-func createTestEbookID(t *testing.T, ts *httptest.Server, token string) string {
+// createTestMediaItemID creates a test media item and returns its ID
+func createTestMediaItemID(t *testing.T, ts *httptest.Server, token string) string {
 	// First create a library
 	libReq := map[string]interface{}{
 		"name":        "Test Library",
-		"description": "A test library for ebooks",
+		"description": "A test library for media items",
 		"type":        "ebooks",
 	}
 	libBody, _ := json.Marshal(libReq)
@@ -295,18 +295,18 @@ func createTestEbookID(t *testing.T, ts *httptest.Server, token string) string {
 
 	libData := libResult["id"].(string)
 
-	// Create a test ebook
-	ebookReq := map[string]interface{}{
+	// Create a test media item
+	mediaItemReq := map[string]interface{}{
 		"library_id": libData,
-		"title":      "Test Ebook",
+		"title":      "Test Media Item",
 		"author":     "Test Author",
 		"file_path":  "/tmp/test.epub",
 		"file_size":  1024,
 		"mime_type":  "application/epub+zip",
 	}
-	ebookBody, _ := json.Marshal(ebookReq)
+	mediaItemBody, _ := json.Marshal(mediaItemReq)
 
-	req2, _ := http.NewRequest("POST", ts.URL+"/api/media-items", bytes.NewBuffer(ebookBody))
+	req2, _ := http.NewRequest("POST", ts.URL+"/api/media-items", bytes.NewBuffer(mediaItemBody))
 	req2.Header.Set("Content-Type", "application/json")
 	req2.Header.Set("Authorization", "Bearer "+token)
 
@@ -316,9 +316,9 @@ func createTestEbookID(t *testing.T, ts *httptest.Server, token string) string {
 
 	require.Equal(t, http.StatusCreated, resp2.StatusCode)
 
-	var ebookResult map[string]interface{}
-	json.NewDecoder(resp2.Body).Decode(&ebookResult)
+	var mediaItemResult map[string]interface{}
+	json.NewDecoder(resp2.Body).Decode(&mediaItemResult)
 
-	ebookID := ebookResult["id"].(string)
-	return ebookID
+	mediaItemID := mediaItemResult["id"].(string)
+	return mediaItemID
 }