feat: add Tailcall config generator page

[michellehumes]

/claim #373

Summary

Adds a new /app/config Docusaurus page for generating Tailcall runtime configuration from the live Tailcall JSON schema.

What changed

• Fetches the current .tailcallrc schema from the Tailcall main branch.
• Renders schema-driven controls for config sections, nested objects, booleans, numbers, arrays, strings, and enum values.
• Resolves basic local $ref, allOf, anyOf, and oneOf schema composition.
• Prunes empty values from the generated output.
• Shows a live JSON preview.
• Adds a download action for .tailcallrc.json.

Verification

• npm run format:check -- src/pages/app/config.tsx
• npm run build
• Served /app/config/ locally and confirmed HTTP 200.

Note: npm run typecheck still reports existing repository type errors outside this new page. The new page was adjusted so it is not part of the remaining typecheck error list.