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/dashboard/update-preferences.yml

@@ -0,0 +1,36 @@
+info:
+  name: Update Dashboard Preferences
+  type: http
+  seq: 2
+http:
+  method: POST
+  url: '{{base_url}}/api/dashboard/preferences'
+  auth: inherit
+runtime:
+  scripts:
+  - type: tests
+    code: "test(\"status must be 200 with valid request\", function() {\n    expect(res.status).to.eql(200);"
+
+docs: |-
+  Update dashboard preferences for the authenticated user.
+  
+    **Endpoint**: POST /api/dashboard/preferences
+    **Auth**: Required (Bearer token)
+  
+    ## Request Body
+  
+    | Field | Type | Required | Description |
+    |-------|------|----------|-------------|
+    | library_id | string | Yes | Library UUID |
+    | hidden_sections | array | No | Section IDs to hide |
+    | section_order | array | No | Section IDs in custom order |
+    | items_per_section | int | No | Items to show per section (10-50) |
+  
+    ## Example Request
+  
+    ```json
+    {
+      "library_id": "cc23c3a7-f8fb-451a-a78d-2a16df1b725a",
+      "hidden_sections": ["recently-added"],
+      "section_order": ["continue-reading", "in-progress"],
+      "items_per_section": 25