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/devices/scenarios/Reject Registration - KOReader.yml

@@ -0,0 +1,56 @@
+info:
+  name: Reject Registration - KOReader
+  type: http
+  seq: 16
+
+http:
+  method: POST
+  url: '{{base_url}}/api/devices/reject/reg-uuid-123'
+  auth: inherit
+
+docs: |-
+  ## Reject KOReader Registration
+
+  Rejects a pending KOReader device registration.
+
+  **Method:** POST
+
+  **Endpoint:** /api/devices/reject/:registration_id
+
+  **Authentication:** Required (Bearer token)
+
+  **Path Parameters:**
+  - `registration_id` (string): Example: `reg-uuid-123`
+
+  **Request Body:**
+  Optional rejection reason:
+  ```json
+  {
+    "reason": "Device not recognized or user cancelled"
+  }
+  ```
+
+  **Response:**
+  - `registration_id` (string): Rejected registration UUID
+  - `device_name` (string): KOReader device name
+  - `device_type` (string): `koreader`
+  - `status` (string): `rejected`
+  - `rejected_at` (string): Rejection timestamp
+
+  **Status Codes:**
+  - 200: Rejected successfully
+  - 401: Unauthorized
+  - 403: Forbidden
+  - 404: Registration not found
+
+  **KOReader Rejection Handling:**
+  - KOReader app displays rejection message
+  - User can initiate new registration
+  - Previous device identifier can be reused
+  - No data is lost on the device
+
+  **Common Reasons:**
+  - User didn't initiate registration
+  - Wrong device type selected
+  - Testing/sample registration
+  - Security concerns