[ppgranger]

What

Fix hook interpreter selection and marketplace update instructions, add documented Codex and optional Texio workflows, and bump the patch version to 3.0.1.

Why

A hook launched with a supported Python could still rewrite commands through an older python3 on PATH, breaking their execution. Marketplace update notices also suggested a CLI command that may not be installed on the user's PATH.

Fixes #68
Fixes #74
Fixes #75
Fixes #76

How

• Invoke the wrapper through shell-quoted sys.executable. Check Python 3.10+ before runtime imports; unsupported hook interpreters emit a clear diagnostic and remain non-blocking.
• Use existing marketplace detection to recommend /plugin update token-saver within Claude Code, retaining token-saver update for manual installs.
• Document an opt-in Codex wrapper/AGENTS.md workflow, including exit-status behavior and limitations. This does not add an automatic Codex hook.
• Add a disposable-file Texio 0.1.3 evaluation with measured command/output overhead and explicit limits. It adds no runtime dependency or whole-task token-savings claim.
• Synchronize version manifests, the benchmark header, and the 3.0.1 changelog.

Validation

• Full suite: 1,940 passed, 12 skipped; also passed with encoding warnings treated as errors.
• Ruff 0.15.15, Pylint 4.0.5, structural style, mypy, and version consistency checks passed.
• Python 3.9.6 entry-point checks and Codex success/failure examples verified with temporary profiles.
• Jekyll build and rendered metadata/link/sitemap checks passed; Texio trial verified without modifying the original fixture.

Checklist

• ruff check . bin/token-saver passes
• ruff format --check . bin/token-saver passes
• python3 -m pytest tests/ -q passes
• New runtime behavior has regression tests
• No secrets or credentials in the diff