feat: add comprehensive Bruno API tests for annotations

- Add complete Bruno collection for notes API (5 endpoints)
- Add complete Bruno collection for highlights API (5 endpoints)
- Include detailed request/response documentation
- Add proper validation examples and error cases
- Support both media-items and ebook endpoint testing
- Add environment variable support for dynamic IDs

bruno/highlights/Update Media Highlight.bru

@@ -0,0 +1,60 @@
+meta {
+  name: Update Media Highlight
+  type: http
+  seq: 4
+}
+
+put {
+  url: {{base_url}}/api/media-items/{{media_item_id}}/highlights/{{highlight_id}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "selection_text": "This is the updated highlighted text.",
+    "start_position": "page:45:offset:125",
+    "end_position": "page:45:offset:150",
+    "color": "#ffeb3b",
+    "note_id": ""
+  }
+}
+
+script:post-response {
+  onResponse(res);
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+docs {
+  ## Update Media Highlight
+  
+  Updates an existing highlight.
+  
+  **Method:** PUT
+  
+  **Endpoint:** /api/media-items/:id/highlights/:highlightId
+  
+  **Path Parameters:**
+  - `id` (string): Media item ID
+  - `highlightId` (string): Highlight ID
+  
+  **Request Body:**
+  - `selection_text` (string): Updated highlighted text (required, 1-5000 chars)
+  - `start_position` (string): Updated start position (required, max 100 chars)
+  - `end_position` (string): Updated end position (required, max 100 chars)
+  - `color` (string): Updated highlight color in hex format (optional)
+  - `note_id` (string): Updated associated note ID (optional)
+  
+  **Response:**
+  - Updated highlight object with all fields
+  
+  **Status Codes:**
+  - 200: Success
+  - 400: Invalid request
+  - 401: Unauthorized
+  - 404: Highlight not found
+}