feat(labels): plain-sentence policy labels, install warnings and witness notes (VOICE-3a)

[jothimani-rajendran]

What

VOICE-3a (org-plan plan/site-plain-voice.md). This PR rewrites the label and warning text that the site and chock install show, following the voice style guide in org-plan discovery/2026-10-18-site-voice-audit.md. The new text has no semicolon chains, no colon chains, and no jargon such as "judged", "fails open" or "witnessed". No label claims more than it did before, every caveat is kept, and "tested" (seen in a live run) stays separate from "vendor docs only".

• plugin/bundle_grade.py: changes the advisory text and the Stop-only gate reach ("blocks at turn end only. It does not check a file write when it happens"). A guard next to a gate is now joined with ". " instead of "; ".
• install/package.py and install.json: the tier-table prefix now reads "best-effort, and a hook error lets the action through (agentseam vendor-docs): " instead of "fail mode open". The words for each fail mode now live in data. The unasked note becomes ". The ask is not enforced here (…)".
• Devin's prefix (install.json and bundle_build._QUALIFIER) is rewritten the same way.
• install/data/warnings.json: 15 warnings, install/data/claude_plugin.json: 6 strings, and data/witnesses.json: 6 plugin-hook witness notes. Quoted output, ids, record paths and commits are unchanged.
• Tests that assert exact copy now assert the new text, just as strictly. The plugin_targets goldens were regenerated with CHOCK_REGEN_GOLDENS=1 on Python 3.13.
• CHANGELOG.md is not edited. A changelog.d/ fragment is added instead.

The words the site's label tags match on ("shell command", "file writes", "turn end", "advisory") are kept. chock-catalog's tools/label_honesty.py is updated in the companion catalog PR so it reads both the old and the new wording.

Definition of done

• chock sync --repo . --check clean
• pytest -q (Python 3.13): 4683 passed, 97 skipped, 1 failed on the first run (the 300-line budget in test_plugin_install_targets.py). That is fixed in the third commit, and the file and test_repo_standards.py were re-run: 44 passed.
• Touched manifests: none. A changelog.d/voice-3a-plain-labels.md fragment is added.
• ruff check and ruff format --check clean on src and tests. tools/check_literal_duplication.py is clean.
• chock check and the acceptance suite were not run locally. CI runs them.

Claims

• No surface is described as enforcing more than it installs. Only wording changed. Grades and keywords are unchanged.

Owner approval gate: this PR stays in draft until the owner approves the wording list in the org-plan handoff.

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