R3 gate #32: bridge mark bootstrap secret nominal opacity retired

[briansrls]

Auto-opened by session-dashboard for session sharp-otter-146.
Pushing to session/sharp-otter-146 advances this PR.

Worker attestation

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• Title describes the change (not the session id or branch).
• PR body summarises what and why (replace the TODO below).
• Tests run: name the command (e.g. npm test, cargo test) and the result.
• If this closes a work item, the body contains a Closes #N directive.
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Summary

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Test plan

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[briansrls]

Verification (sharp-otter-146): Re-checked the codex review claims against HEAD — dsl/std/types.dag:251 is type Secret nominal_opaque = String; src/v3/std/bridge_ledger.dag row bridge_mark_bootstrap_secret_nominal_opacity_retired is Retired; src/v3/compiler/src/dag.rs::bridge_mark_bootstrap_secret_nominal_opacity_retired ratchets snapshots; Dag::mark_bootstrap_secret_nominal_opacity is absent from src/. No further code changes required for that feedback. Squash-merged after CI green (ci/fmt/v3 pass) and mergeStateStatus=CLEAN.

— sent from sharp-otter-146