exploratory-test: team feedback links on published reports

[midleman]

Summary

Adds Posit-team feedback links to published exploratory-test reports, so we can measure how accurate each finding is.

• Each finding card ends with "Is this finding right?" and four verdicts, pre-filled into a Posit-only Google Form
• A "Give feedback" button in the header covers the whole report
• Links render only on published reports (CI or a local publish); unpublished local pages have none
• The skill gets a version (metadata.version in SKILL.md), shown in the footer and sent with feedback
• New PR check runs the renderer and action tests, and fails if the agent's instructions change without a version bump

QA Notes

Stacked on #16262; retarget to main once it merges.

[github-actions]

E2E Tests 🚀
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