Add GET /v2/profile endpoint to channel-access-token.yml

@mokuzon is already working on this.

Since Mar 25, 2026.

## Feature Request

**Is your feature request related to a problem? Please describe.**
The `channel-access-token.yml` currently does not include the `GET /v2/profile` endpoint, which means auto-generated SDKs (like line-bot-sdk-ruby) lack a method to retrieve user profile information.

When we want to get user information (userId, displayName, pictureUrl, statusMessage) after LINE Login authentication, we have to manually implement HTTP requests since no SDK method exists for this endpoint.

**Describe the solution you'd like**
Please add the following endpoint to `channel-access-token.yml`:

- **Endpoint**: `GET https://api.line.me/v2/profile`
- **Operation ID**: `getUserProfile`
- **Authentication**: Bearer token (access token with `profile` scope)
- **Response Model**: `GetUserProfileResponse`
- Required: `userId` (string), `displayName` (string)
- Optional: `pictureUrl` (string), `statusMessage` (string)

**Reference**: https://developers.line.biz/en/reference/line-login/#get-user-profile

**Describe alternatives you've considered**
I've considered the following alternatives, but none are ideal:
1. SDK users manually implement requests using an HTTP client
2. Fork the SDK and extend it independently
3. Add methods manually without using auto-generation

By including it in the official OpenAPI specification, all SDKs can support this feature consistently.

**Additional context**
This endpoint is part of the LINE Login API and is widely used. Adding it would enable more complete LINE Login support across all SDKs, including line-bot-sdk-ruby.