quantmodel — Add custom Meta report controls and browser state

Objective

Add custom Meta report controls and browser state.

Notes: Added Custom Meta controls with fail-closed canonical config validation, base64url share state, URL-over-localStorage precedence, explicit save/reset, corrupt-state recovery, and Node-backed browser contract tests.

Approach

Reuses existing report research/findings/custom-meta-browser-controls-t260.md — tables/metrics preserved verbatim via source_report pointer. Body below summarizes grounded evidence from that report and adjacent artifacts.

Files / code / data changed

No commit SHA confidently associated with t260 in sampled log [reconstructed — uncertain].
Source report: research/findings/custom-meta-browser-controls-t260.md
Task-history entry: research/findings/task-history.json#t260

Results

Conclusions and metrics are in research/findings/custom-meta-browser-controls-t260.md; see detail page for preserved tables/metrics.

Conclusions

Added Custom Meta controls with fail-closed canonical config validation, base64url share state, URL-over-localStorage precedence, explicit save/reset, corrupt-state recovery, and Node-backed browser contract tests.

Problems / follow-ups

See source report or PR discussion for follow-ups. No unsupported follow-ups fabricated.