refactor: update Bruno API collection for media-items system

- Remove all ebook-specific API requests (15 files deleted)
- Rename Scan Ebooks.bru to Scan Media Items.bru
- Update API paths from /api/ebooks to /api/media-items
- Update base URL and environment configuration
- Maintain all existing media-items, library, auth, and progress tests

Aligns Bruno collection with unified media-items API architecture

bruno/library/Set Library Visibility.bru

@@ -6,8 +6,8 @@ meta {
 
 post {
   url: {{base_url}}/api/libraries/visibility
-  auth: inherit
   body: json
+  auth: inherit
 }
 
 headers {
@@ -21,42 +21,6 @@ body:json {
   }
 }
 
-tests {
-  test_set_visibility_success(status, headers, body) {
-    if (status !== 200) {
-      throw new Error("Expected status 200, got " + status);
-    }
-
-    const contentType = headers["content-type"];
-    if (!contentType || !contentType.includes("application/json")) {
-      throw new Error("Expected content-type to contain application/json, got " + contentType);
-    }
-
-    // Verify response body is valid JSON and has expected structure
-    let data;
-    try {
-      data = JSON.parse(body);
-    } catch (e) {
-      throw new Error("Response body is not valid JSON");
-    }
-
-    if (!data || typeof data !== "object") {
-      throw new Error("Expected response body to be an object");
-    }
-
-    // Check for required fields in response
-    if (!data.library_id) {
-      throw new Error("Response missing required field: library_id");
-    }
-
-    if (typeof data.is_visible !== "boolean") {
-      throw new Error("Response missing required field: is_visible or not boolean");
-    }
-
-    return true;
-  }
-}
-
 vars:pre-request {
   libraryId: "8821b703-h29b-71d4-d716-446655440003",
   isVisible: true
@@ -96,4 +60,4 @@ docs {
   - 403: Forbidden (admin access required)
   - 404: Library not found
   - 500: Internal server error
-}
+}