0.141.b21f0.1.mod

Mod refresh release for upstream b21f0e7a98c05a570cc227e2ec62a2e29c3a7225.

• Refreshes the compact-fix fork to the pinned upstream commit above.
• Preserves fork-local remote compact configuration, retry, fallback, service-tier, V1/V2 parity, and .mod version display behavior.
• Preserves session-only /model and persistent /modelp behavior.
• Builds and uploads the Linux codex CLI artifact.
• Tests were not run for this release unless explicitly requested; release validation uses the Cargo release build and ./codex --version.
• Bazel was not used; this release uses the Cargo release build path only.