feat: ingest GitHub issue comments in RAG pipeline

[Sayan4496]

Summary

Adds a new KFP component to ingest GitHub Issue comments and append them to issue content for indexing.

Changes

• New component download_github_issue_comments
• Appends comments including author, timestamp, and comment URL (citations)
• Pipeline updated to support Issues + Comments ingestion flow

Testing

• Local syntax check: python -m py_compile pipelines/kubeflow-pipeline.py
  -Fixes Feat: Ingest GitHub Issue Comments into RAG pipeline #9

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign franciscojavierarceo for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[franciscojavierarceo]

is this similar to #8?

[Sayan4496]

Good question.
PR #8 already fetches issue comments inside download_github_issues.

This PR restructures comment ingestion into a separate pipeline component (download_github_issue_comments) to improve modularity and allow configurable comment enrichment as an independent stage in the RAG pipeline.

The goal is to separate concerns:

Issue retrieval

Comment enrichment

Chunking & embedding

Happy to adjust this as a refactor of the existing component if that direction is preferred.