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/Initiate Device Registration.yml

@@ -0,0 +1,12 @@
+info:
+  name: Initiate Device Registration
+  type: http
+  seq: 1
+http:
+  method: POST
+  url: '{{base_url}}/api/devices/register'
+  auth: none
+  body:
+    type: json
+    jsonBody: "{\n    \"device_name\": \"My Kindle Paperwhite\",\n    \"device_type\"\
+      : \"koreader\",\n    \"device_identifier\": \"kindle-pw5-hardware-id-12345\""