feat: add Tailcall config generator

[chinook1001]

/claim #373

Summary

• Add a Tailcall runtime configuration generator at /app/config
• Load the live Tailcall runtime JSON schema dynamically and use it for field descriptions/link type options
• Generate JSON, YAML, and GraphQL SDL output with copy and download actions
• Add starter, production, and gRPC presets plus link/header controls
• Link the generator from /playground

Closes #373

Verification

• npm run build
• npm run format:check -- src/components/config/ConfigGenerator.tsx src/pages/app/config.tsx src/components/playground/Playground.tsx src/constants/routes.ts src/constants/titles.ts
• Browser check on http://127.0.0.1:3010/app/config at desktop and narrow mobile-like window widths

Notes

• npm run typecheck still fails in existing unrelated areas: missing generated GraphQL types in publish-externals, DocSearch typings in src/theme/SearchBar, and Algolia client typing in src/theme/SearchPage. The new config generator and touched playground fetcher type cleanly after this change.

[chinook1001]

/claim #373