Deduplicate agent docs and READMEs, fix stale docs

[kaareal]

What

• No duplication: root and web AGENTS.md now route to README.md / PRODUCT.md / DESIGN.md / THEME.md instead of restating toolchain, stack, commands, design rules or product description. Service READMEs link to the root README for Volta/pnpm setup.
• Generator removed: the generator directory hasn't existed since 2020. Dropped it from AGENTS.md, PRODUCT.md, DESIGN.md (Parity Rule), the API README (bedrock generate docs) and the broken generate script in services/web/package.json.
• Stale docs fixed:
  • web SERVER_PORT default is 2200, not 2300
  • config is injected as window.__ENV__, not window.__env_conf
  • index.html is the entry point (not src/index.html); serve/dev.js doesn't exist
  • API docs flow is openapi.json + pnpm docs:generate + MDX pages (not src/routes/__openapi__)
  • THEME.md and PRODUCT.md now include the Bricolage Grotesque heading font and Indigo default

Reviewer notes

• Docs only, plus one removed npm script. No runtime code changed.
• The rewritten docs sections (API docs portal, env injection) were checked against the source, not by running pnpm docs:generate or the app.
• Every relative link and file path in tracked markdown resolves, except credentials.conf, which Git ignores on purpose.

[github-actions]

API Changes

No changes.