feat(product): build dark mode IDE mockup with syntax highlighting

[amoduenechojo]

Summary

Implements the Solidity contract IDE mockup for the product/marketing page:

• components/product/ContractMockup.tsx — MacOS-style window frame (traffic-light
  dots, title bar), dark-mode-optimized Solidity/TypeScript syntax highlighting via
  PrismJS, loading skeleton, error state with retry, and copy-to-clipboard.
• hooks/useContractMockup.ts — fetches the snippet (TanStack Query) and manages
  copy-to-clipboard state.
• services/contractMockupService.ts — API client; no inline mock data in the
  component.
• app/api/product/contract-mockup/route.ts — backend data source for the snippet.
• types/contractMockup.ts — shared ContractSnippet type.

Architecture follows the existing Component → Hook → Service layering used
throughout the codebase (e.g. PaymentLock → useCurrencyConversion → fxService).

Testing

• Added unit tests for the component, hook, and service (11 tests, all passing).
• tsc --noEmit and ESLint clean on all new/changed files.
• Manually verified in the dev server: window chrome, dark syntax highlighting,
  loading/error states, and copy button all behave correctly.

Closes #325

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[johdanike]

Fix cicd build issues