@razroo/iso-route v0.3.1

Patch — `standard` preset Codex default

The `standard` preset now pins `default.targets.codex` to
`openai/gpt-5.4`, so a Codex user running `extends: standard` with
no further overrides gets a natively-routable OpenAI model instead of
the Anthropic default flattened as-is. A Codex setup with no
overrides previously needed the user to remember to add a codex
override for the default tier to get anything usable.

Also tightens the preset header comment to cite the specific
harness/provider docs used to verify each pick: Claude Code model
config, Cursor models, Codex models, OpenCode models.

Content-only change — no API, no CLI, no parser changes.
Upstream dep ranges (`@razroo/iso` pins `^0.3.0`) accept this
release automatically.