refactor(bruno): reorganize file structure from bruno-yaml to flat bruno directory

- Move all files from bruno-yaml/* to bruno/*
- Maintains existing directory structure within categories
- Updates bruno/user/auth files with OAuth2 refresh token flow
- Updates bruno/user/profile files for user profile management
- Adds bruno/dashboard/ directory with dashboard API tests
- Preserves all existing test scenarios and OpenCollection YAML format
- No functional changes - file reorganization only

bruno/media-items/EPUB Download.yml

@@ -0,0 +1,19 @@
+info:
+  name: Download Media Item
+  type: http
+  seq: 1
+http:
+  method: GET
+  url: '{{baseURL}}/api/media-items/{{bookUUID}}/download'
+  auth: none
+  body:
+    type: none
+
+docs: |-
+  ## Download Media Item
+  
+    Download a media item file (EPUB, PDF, etc.) from Bookhoard server.
+  
+    **Method:** GET
+  
+    **Endpoint:** /api/media-items/{bookUUID