feat: basic holepunch metrics

[Frando]

Description

This adds two metrics:

• remote_holepunch_attempt counts the number of remotes for which we initiated holepunching.
• remote_holepunch_success counts the number of remotes where we initiated holepunching and had success

Both are either increased by 0 or 1 during the lifetime of a RemoteStateActor, never more. We incrase _attempt once on the first time when holepunching is initiated. We increase _success once if a new IP path is opened whose remote address is part of the last holepunching round.

I'm not entirely sure if this logic is fully sound, but it's the best I could come up with so far.

Fixes #3695

Breaking Changes

Notes & open questions

Change checklist

• Self-review.
• Documentation updates following the style guide, if relevant.
• Tests if relevant.
• All breaking changes documented.
  • List all breaking changes in the above "Breaking Changes" section.
  • Open an issue or PR on any number0 repos that are affected by this breaking change. Give guidance on how the updates should be handled or do the actual updates themselves. The major ones are:
    • quic-rpc
    • iroh-gossip
    • iroh-blobs
    • dumbpipe
    • sendme

[github-actions]

Documentation for this PR has been generated and is available at: https://n0-computer.github.io/iroh/pr/3748/docs/iroh/

Last updated: 2025-12-10T12:24:53Z