Ordered actions, help text and serial execution

What's Changed

• Update shared-actions pins to 2f90d10 by @leynos in #528
• Derive version-sensitive test contracts from the crate version by @leynos in #532
• Use shared-action RUSTFLAGS passthrough by @LodyAI[bot] in #507
• Make the locale test stub strict about unexpected variable reads (#489) by @leynos in #502
• Bump shared-actions pins to 8add2d9 for the MSI pre-release fix by @leynos in #535
• Derive the shared-actions pin in the toolchain contract by @leynos in #540
• Address the outstanding review comments from #526 by @leynos in #537
• Stage cargo-binstall archives and simplify the binstall metadata by @leynos in #534
• Give the workspace fallback switch an injectable env seam (#487) by @leynos in #498
• Document CommandArg and remove unused BuildTargets::is_empty (#75) by @leynos in #354
• Convert StringOrList helper functions to methods (#73) by @leynos in #353
• Make PATHEXT normalisation testable on any host (#485) by @leynos in #503
• Address PR #515 review follow-ups by @leynos in #530
• Stop the mock environment mutating the real process environment (#490) by @leynos in #497
• Extract vars registration helper from from_str_named (#79) by @leynos in #355
• Restore standard filter integration tests (#520) by @LodyAI[bot] in #521
• Give home-directory resolution an injectable env seam (#486) by @leynos in #499
• Reduce GlobEntryResult alias to module visibility (#174) by @leynos in #356
• Link the project website from the README and package metadata by @LodyAI[bot] in #546
• Add proptest property tests for expand_foreach (#295) by @leynos in #359
• Scope glob metadata capability to literal pattern prefix (#173) by @leynos in #357
• Extend expand_foreach test coverage (#296) by @leynos in #358
• Prevent manifest fixture overwrites (#61) by @LodyAI[bot] in #545
• Allow rules to execute ordered command lists (#550) by @leynos in #554
• Adopt OrthoConfig v0.9.0 by @leynos in #558
• Add Ninja snapshot test for command_available expansion (#310) by @leynos in #360
• Make subprocess stderr routing an explicit policy (#340) by @leynos in #553
• Add target descriptions and netsuke help targets (#551) by @leynos in #555
• Support serial dependency ordering (3.14.3) (#552) by @LodyAI[bot] in #557
• Improve config-load observability (#304) by @LodyAI[bot] in #547
• Split CHANGELOG into v0.1.0-beta1 and v0.1.0-beta2 releases by @leynos in #568

Full Changelog: v0.1.0-beta1...v0.1.0-beta2