Add breeze pr stats command for open PR statistics by area

[potiuk]

Add a new breeze pr stats command that produces aggregate statistics of open PRs in the Airflow repo, split by area label. The command uses GraphQL to fetch all open PRs and displays two tables:

1. Triaged PRs — Final State: Shows triaged PRs that were closed or merged since 2026-03-11, with counts and percentages for closed, merged, and author-responded.

2. Triaged PRs — Still Open: Shows all open PRs grouped by area with draft/non-draft counts, contributor counts, triage status, response rates, ready-for-review status, time since triager drafted the PR, and time since the author's last interaction.

Features:

• Cached interaction data (keyed by updated_at) to avoid re-fetching unchanged PRs on subsequent runs
• --clear-cache flag to force fresh data
• Detects triager draft conversions via GraphQL timeline events
• Tracks closed vs merged triaged PRs with area breakdown
• Footer header rows on both tables for readability

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Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

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• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.

[github-actions]

Backport failed to create: v3-2-test. View the failure log Run details

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
❌	v3-2-test

You can attempt to backport this manually by running:

cherry_picker 8c4c990 v3-2-test

This should apply the commit to the v3-2-test branch and leave the commit in conflict state marking
the files that need manual conflict resolution.

After you have resolved the conflicts, you can continue the backport process by running:

cherry_picker --continue

If you don't have cherry-picker installed, see the installation guide.