feat!(tickets): tickets that pass shared secrets to N0DES_SECRET env var builder method

[b5]

Description

• introduces a N0desTicket that binds together the n0des remote endpoint to dial, plus a shared secret. We're drafting off of iroh-docs WriteTickets here
• introduces a new Client capability to reflect permissions derived from a shared secret
• adds methods to separate shared secret construction from the existing "local-private, registered public" key infra we have
• Adjusts the builder to no longer take a remote: impl Into<EndpointAddr> arg, replaces with a remote method on the builder
• adds a new method for creating clients from a N0desTicket:

// this will read N0DES_SECRET env var, expects a N0desTicket:
let client = Client::builder(&endpoint)
                .secret_from_env()?
                .build()
                .await?;

• adds a ticket method to ClientBuilder to provide a ticket directly, shares implementation with secret_from_env

Breaking Changes

• ClientBuilder.build no longer takes an address argument. Use ClientBuilder.remote(address) instead

Notes & open questions

Change checklist

• Self-review.
• Documentation updates following the style guide, if relevant.
• Tests if relevant.
• All breaking changes documented.

[github-actions]

Documentation for this PR has been generated and is available at: https://n0-computer.github.io/iroh-n0des/pr/50/docs/iroh_n0des/

Last updated: 2025-11-20T16:46:30Z

[Frando]

Looks good in general, some minor points in comments