Add labels field to Pull Requests response

[Copilot]

Pull Requests were missing labels in their response data, while Issues already included them.

Changes

• PullRequest struct: Added Labels field with GraphQL query labels(first: 100)
• DataFrame output: Added labels field as json.RawMessage array in Frames()
• Tests: Updated test fixtures with label data

Implementation

Mirrors the existing Issues pattern:

Labels struct {
    Nodes []struct {
        Name string
    }
} `graphql:"labels(first: 100)"`

Labels are marshaled to JSON arrays and appended to the DataFrame, enabling label-based filtering and visualization in Grafana dashboards.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Feature Request: Add Labels to Pull Requests Response</issue_title>
<issue_description>In the same with Issues does, it would be nice to have the array of labels returned with Pull Requests.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Feature Request: Add Labels to Pull Requests Response #525

---

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[zoltanbedi]

LGTM