The router-agnostic refactor turned useTRPC from a destructured const into a
wrapper function; its body was unexercised, dropping client.ts below the 80%
coverage floor. Stub the tRPC context factory and assert useTRPC() delegates
to the shared proxy — client.ts back to 100%.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK