fix(site): make policy selection and evidence recovery reliable

[KIM3310]

User-visible changes

• Use native keyboard-accessible policy buttons with one pressed selection.
• Clear every dynamic section when evidence loading fails. Add a working retry and restore focus after recovery.
• Label capacity-rejected HBM results as Not run, without misleading zero-value chart bars.
• Add a committed, dependency-free Chrome browser regression command.

Verification

• Independent AI landing review: PASS+NOTES at 11e7392789da37041880b8b206ddbfcffa69eecb against f40e114c5ed15942f8d797f74df6e95182b2ffa3.
• Stable patch ID: 55c9eaa49a5ec14b5c89bd7e7113c0aa17244aa5.
• Full native make verify: 189 tests, 96.58% coverage, Ruff, formatting, strict mypy, deterministic evidence, site checks and distribution checks passed.
• The committed Chrome suite passed 9/9 cases independently. It covers keyboard, mouse, accessibility-tree states, blocked/503/malformed/partial JSON, failed retry, successful recovery and responsive layout.
• Failing-first browser regressions were committed before the fix. Existing tests and the coverage floor were not weakened.
• Five protected result/measurement/evidence files remain byte-identical to baseline.

Scope and limits

Only the static client and its browser check change. Simulator code, schema, scenarios, dependencies and historical numeric evidence do not change. This is not a new hardware benchmark or a formal accessibility certification.

The browser suite is a separate command; make verify and existing CI do not invoke it. The existing same-origin checked-in JSON trust boundary and narrow grid-gap spacing remain. Hosted checks and actual Cloudflare artifact verification are separate release gates. No deployment is claimed by this PR description.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[KIM3310]

Independent AI landing review: PASS+NOTES.

Reviewed head 11e7392789da37041880b8b206ddbfcffa69eecb, base f40e114c5ed15942f8d797f74df6e95182b2ffa3, stable patch ID 55c9eaa49a5ec14b5c89bd7e7113c0aa17244aa5.

A separate reviewer, who did not author the code, inspected the full diff and independently ran the native verification and committed Chrome suite. Results were 189 tests, 96.58% coverage, all native gates, and 9/9 browser cases. The served source and five protected historical result/evidence files matched their expected bytes. No weakened tests, new suppressions or blocking findings were found. The release coordinator inspected the actual diff, review and evidence.

Notes: browser checks remain a separate manual command; the existing trusted checked-in JSON boundary and narrow grid-gap spacing remain. No new hardware benchmark, cross-browser or formal accessibility certification is claimed. This is not an external security audit. Remote CI, merge identity and actual Cloudflare upload remain separate release checks.