fix(ssh-config): unquote Host aliases so ssh -G can resolve them

[Petyok]

What

Host "web" in ~/.ssh/config was listed as the alias "web" — quotes included — so resolve_host ran ssh -G '"web"' and got back hostname contains invalid characters. The host showed up in the list and could not be connected to. OpenSSH strips those quotes when matching; listable_host_alias now does too.

How it was found

By the first oracle test in the resolver: a differential test that takes every alias list_hosts() returns and resolves it through the real ssh binary, asserting it lands back on the block it came from. The alias parser is the one part of host resolution sshub implements itself — resolve_host already delegates to ssh -G, but OpenSSH has no "enumerate hosts" mode to delegate the listing to.

The nine existing unit tests for this parser all passed: they check the code against in-repo assumptions, which is exactly what does not catch an assumption that was wrong to begin with. The differential test failed on its first run, and was re-verified red against the unfixed parser before being called done.

Also in this PR

docs/oracle-tests.md writes the pattern down, with the subsystems that still have an unused external oracle:

Subsystem	Oracle	Status
ssh/resolver.rs alias listing	ssh -G	this PR
known_hosts.rs	ssh-keygen -F / -R	already done
ssh/export.rs	round-trip the rendered snippet through ssh -G	missing
ssh/keyfile.rs	ssh-keygen -y / -l	missing
import/{putty,mremoteng,termius_csv}.rs	a real export from that tool	fixtures are agent-authored

AGENTS.md and CLAUDE.md point at it.

How tested

• just test — 671 + 73 + 44 + 1, all green, exit 0
• cargo fmt --check, cargo clippy --all-targets — 0 warnings
• New test verified red without the fix: ssh -G rejected listed alias "\"quoted\"": hostname contains invalid characters
• The test skips itself when no ssh binary is present

🤖 Generated with Claude Code

Written by Claude Opus 5 (Claude Code) on behalf of the maintainer.