docs(town): align the current manual, trace viewer and build checks

Description

The pitch.

## Summary

Bring the public entry points into agreement with the rebuilt Town code and its actual evidence boundaries:

- Replace the legacy web manual with current Lab/Track/Path install, run, verification and existing-agent instructions.
- Update README, architecture, operators, convergence and contributor guidance; add a terminal-friendly existing-agent guide and clearly date historical material.
- Explain partial receipt validity versus full-coverage badge eligibility, local key commitment versus independent observation, external release/rerun limitations, remote networking and kiosk controls.
- Import current TownEvent traces without confusing them with legacy showcase fixtures; scope correlation by run and subject and repair React lifecycle/lint failures.
- Align Node/deployment/environment guidance and make dashboard lint and production build required CI checks.

## Merge order

Please merge this manual last, after the behavior it documents:
- #261 evidence/strict Path
- #259 runtime/provenance
- #258 imports/on-ramp
- #262 viewers/board
- #257 catalog writes
- #260 schemas/distributions/CI

All branches are independently based on official main, not a long PR stack. An independent local merge of all seven heads exactly matches the tested integration tree without conflicts.

## Verification

Base: `53178b9c780d7a7dd6ce723131c4250de03908dd`.

Standalone manual branch, Node 22.23.2:
- `npm ci --ignore-scripts --no-audit --no-fund`
- `npm test` — 49 passed.
- `npm run typecheck` — passed.
- `npm run lint` — passed, no rule suppression.
- `npm run build` — passed, 14 static pages generated.
- `git diff --check` — clean.
- All 23 local Markdown file links resolve; independent documentation review cleared command, version, scope and reproduction claims.

Combined remediation separately passed 817 Python tests on both Python 3.12 and a clean Python 3.11 wheel, 71 dashboard tests, typecheck, lint and build. Documented Lab, Track, packaged BYOA and strict A2A controls were executed. Production-browser inspection loaded a real current Track trace with two agents and three messages.

## Deliberately not claimed

Town fixtures, local tests and a bounded real-agent diagnostic are not proof of external adoption, full NANDA integration, universal protocol conformance or independent operator acceptance. Convergence documents the remaining useful outside pilot, real discovery components, observer policy and deployment resource decisions. No production service/database, agent installation or model-provider configuration was changed by this PR.