⚙️ [Maintenance]: Harden workflow permissions and add YAML perf review harness

[Marius Storhaug (MariusStorhaug)]

This change hardens workflow secret and permission handling for PR paths and adds a repeatable Profiler-based performance harness for YAML command regressions.

Changed

• Replaced broad reusable-workflow secret inheritance with explicit mapping for required secrets in .github/workflows/Process-PSModule.yml.
• Split workflow execution into PR and release-capable paths so open-PR runs use reduced permissions, while closed-PR/scheduled/manual paths retain publish-capable permissions.
• Added ests/tools/Invoke-YamlPerfReview.ps1 to run repeatable baseline/regression performance scenarios for core YAML commands.

Validation

• Confirmed branch cleanliness and push status.
• Executed targeted Pester suites for parser/merge/removal paths after workflow/perf tooling changes.
• Executed Profiler baseline and regression runs using the new harness and enforced the >5% slowdown gate.

Why base is

elease/v1.0.0

These changes are for the in-flight v1.0.0 release line and are intended to support PR #47 hardening and release-readiness work without mixing with unrelated main branch changes.