Opus stage-339 review SHOULD-FIX items:
1. server.py: drop 'unsafe-eval' from CSP report-only policy.
Verified by grepping all production JS — zero matches for eval(),
new Function(), or string-form setTimeout/setInterval. Keeping it
was a gratuitous privilege.
2. server.py: add https://cdn.jsdelivr.net to script-src + style-src.
index.html loads Prism/xterm/katex from this CDN with SRI hashes —
without the allowance every page load fires known-good CSP violations
that drown out real signal once a collector is wired.
3. api/commands.py: sanitize plugin command error. Previously returned
f'Plugin command error: {exc}' which would leak paths/env from
FileNotFoundError('/etc/something/secret.key') etc. Now returns only
the exception type name; full traceback goes to server log.
Test asserts updated to match the new policy shape.
Co-authored-by: Opus advisor <opus-advisor@hermes.local>