Add cross-references, overlapping PR detection, and search to TUI

[andreahlert]

Summary

Why

When triaging a batch of PRs, each one is evaluated in isolation. The maintainer has no way to tell from the TUI whether two open PRs modify the same files (potential merge conflicts or semantic conflicts) or which issues and PRs are referenced in the description. This context matters for triage decisions and today requires manually checking each PR on GitHub.

• Extract #N references from PR bodies and display them as clickable links in the TUI detail panel.
• Fetch all diffs during the loading phase, parse file paths, and detect open PRs that modify the same files. Overlapping PRs are shown in the detail panel with shared file names.
• Add / key to jump to a PR by number.
• New module pr_context.py with 14 unit tests covering extraction and overlap logic.

Test plan

• breeze pr auto-triage --tui --pr 64518 shows References: #64477 in detail panel
• breeze pr auto-triage --tui --max-num 20 then navigate between fix: log and optionally raise on record-level failures in SalesforceBulkOperator #64519 and Add transient-error retry to SalesforceBulkOperator #64575 shows Overlapping PRs: #64575: bulk.py
• Pressing / opens search prompt, typing a PR number jumps to that entry at the top of the list
• Loading phase shows "Fetch diffs" and "Build overlaps" progress steps

---

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

• No

---

• 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.

[andreahlert]

Kept the / search to PR numbers only since it's more of a quick jump shortcut, we can explore proper filtering (by author, labels, etc.) as a separate thing later.

[potiuk]

Can you please rebase to latest main and fix the mypy issue?

[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 979547f 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.