[Haoming9527]

Benchmark setup previously described Windows-only probes as applicable on POSIX, and archived runs from different platforms could be paired without warning. Setup now uses injected platform defaults and explains the skipped PowerShell, module-path and Windows payload checks. Every sweep records platform and composed component configuration even without sealing; unevaluated rows stay unknown and configuration enablement is not presented as a readiness receipt.

Comparison refuses mismatched platform metadata with exit 2. An explicit --allow-cross-platform diagnostic override adds a warning that differences are not a plugin effect. Legacy unknown/unknown archives remain readable. The report and offline panel show the environment facts. The opt-in, non-blocking, model-free tools smoke now has Linux, Windows and macOS legs with separate artifacts.

Fixes #295. Includes the existing #381 commits as an ancestor; merge #381 first. This PR targets main so pull-request validation runs. No model sweep or cross-platform performance conclusion is claimed.

Validation:

• Three portability regressions failed before implementation: POSIX defaults/probes, mismatched platform pairing, and CLI refusal. All pass after the change.
• Six final portability checks pass, including full Linux/macOS setup dry-runs with no spawned process or profile writes and stderr isolation for configuration parsing.
• All 18 deterministic benchmark suites were exercised. The first run passed 17 suites and exposed the old single-platform workflow assertions; the updated three-platform workflow assertions pass (7 checks), with the remaining suites unchanged.
• Workflow structure: 78 checks pass. Source-size and whitespace checks pass.
• Current-head full PR CI passed on Linux, Windows and macOS, plus Node-floor, workflow, size, tools-trial and CI required: run 40113278280 at 80f210e.
• The optional model-free tools smoke passed all three platforms and uploaded separate evidence artifacts: run 40112701731 at 28a80a6. The later commit only merges current main and preserves both changelog entries.

Bilingual benchmark guidance and Unreleased changelog included.

[Thatgfsj]

复审无误，批准合并

The merge-base changed after approval.