TariffWatch v1.3.0: Health endpoint and JSON-LD schema

A solo-founder due-diligence pass wired up `/api/tariffwatch/health` so uptime monitoring has a real endpoint to check, and shipped JSON-LD structured data closing a P0 finding that TariffWatch was shipping zero schema markup.

Like the equivalent fix on EntryProof, wiring up a real health endpoint and shipping JSON-LD schema were both closing gaps that make a product look unfinished to anyone evaluating it seriously. This is particularly consequential for TariffWatch given how many of its visitors arrive during an active, deadline-driven search for help with a federal comment window rather than casual browsing.