Reduce workflow instruction and execution overhead

[xeonvs]

Summary

Apply the minimal workflow findings from the Astra prompting and skills article.

• Load platform, clarification and orchestration owners only for their relevant triggers; avoid duplicate audits and privacy scans for read-only explanations.
• Accept sufficient native completion evidence and native deterministic batching; require durable artifacts only when recovery or evidence needs justify them.
• Clarify existing authorization for scoped local tests and select affected validation during iteration.
• Migrate exact prior generated instruction blocks; preserve customized owners and explicitly review their semantic adoption before prompt apply.
• Prepare 0.9.5 and regenerate the matching plugin bytes. Full plan schema, model settings, privacy and external-action boundaries remain unchanged.

Validation

• Focused upgrade/migration regressions passed, including prior pristine layouts, customized ownership and repeated no-op migration.
• Full maintainer gate: 9/9 stages passed, including all tests and package parity.
• Post-closure structural validation and package check passed.
• Independent semantic review completed; its customized-owner adoption finding was fixed and re-reviewed.
• Pre-push security gate: public-tree privacy, redacted Gitleaks tree and all-ref history passed.

Delivery boundary

PR only: no CI monitoring, merge, tag, release, workflow dispatch or installed-skill update. The maintainer will merge. Marketplace source imports remain a separate release-first step; this branch is not imported as a published release.

Related scoped PRs: tgrep-search #6, xeonvs-engineering #12.