Advance upstream to v0.86.1

[jooh]

Summary

• Bump the pinned upstream/ submodule from v0.86.0 to v0.86.1 (6293ce5879399316f06287e42e710c0f8e5edfef).
• Refresh generated upstream compatibility artifacts: command matrix/reference, CLI metadata, parity inventory, compatibility dashboard, compatibility baseline, compose parity note, and upstream test coverage map.
• Align native lockfile behavior with upstream v0.86.1: trailing-newline writes, semantic frozen comparisons, corrupt-lockfile rejection when generation is requested, and --additional-features exclusion from generated lockfiles unless also configured in devcontainer.json.
• Remove stale TODO_ARGS.md reporting and the repo branding check, then update architecture docs to describe the remaining maintenance tooling.

Validation

• cargo test --manifest-path cmd/devcontainer/Cargo.toml lockfile
• npm run check
• make tests

Notes

• spec/ remains pinned at c95ffeed1d059abfe9ffbe79762dc2fa4e7c2421.
• Local untracked paths .acceptance/, devcontainer-context.sh, and tmp_non_parity/ were left untouched.