feat: add Tailcall configuration generator UI

[Laistragon]

Summary

Adds a new /app/config page for generating Tailcall configuration files from the latest Tailcall runtime config schema.

What changed

• Adds a schema-driven configuration generator page
• Dynamically loads the latest Tailcall runtime JSON schema
• Supports core config sections:
  • server
  • upstream
  • telemetry
  • links
• Adds a live JSON preview
• Adds tailcall.config.json download support
• Adds responsive layout for mobile-friendly usage
• Keeps the generated preview visible while editing larger forms

Validation

• npm.cmd run build
• npx.cmd prettier --check src/pages/app/config.tsx src/pages/app/config.module.css

Note: npm.cmd run typecheck currently fails on existing repository files unrelated to this PR, including publish-externals, playground, and theme/SearchBar types. The new config generator files are not part of those failures.

/claim #373

[Laistragon]

Thanks! I also cleaned the generated files to remove hidden Unicode/BOM warnings and force-pushed the branch into a single clean commit.

Current validation:

• npm.cmd run build
• npx.cmd prettier --check src/pages/app/config.tsx src/pages/app/config.module.css