build(nix): add haqq flake app; add l5, allnodes and p2p seeds; prepare flake for nixos-search; self-hosted runners

[onsails]

Closes: #XXX

Description

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

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[kodiakhq]

This PR currently has a merge conflict. Please resolve this and then re-add the automerge label.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days-before-close if no further activity occurs.