Implement the redesigned GovTool frontend

## Outcome

The frontend delivers the approved site architecture using the new APIs and governance participation model.

## Scope

- Build the approved responsive information architecture
- Integrate Governance API data, metadata states, profiles, activities, and metrics
- Prepare extension points for discussion, off-chain voting, and feeds
- Meet accessibility, performance, analytics, and test requirements

## Acceptance criteria

- [ ] Scope is decomposed into independently deliverable child issues.
- [ ] Architecture and API decisions are linked from this issue.
- [ ] Test, documentation, observability, rollout, and failure behavior are defined where applicable.
- [ ] Epic exit criteria are verified before closure.

## Planning note

This is a 2026 GovTool revamp work item. Its child features and tasks should be added as the scope is refined.

No files, tests, or entry points are named. Start by decomposing the frontend revamp into independently deliverable child issues and linking the architecture and API decisions. Done means the scope, test and documentation needs, observability, rollout, failure behavior, and epic exit criteria are defined and verified.

Written by the indexing model from the issue text.