Web font loading optimizer

Each face reports what the CSS text alone can prove: a missing or blocking font-display, a source list without WOFF2 or without format hints, a missing unicode-range, and whether the face can be preloaded at all. Preload tags carry crossorigin because fonts always need it, and at most 2 are emitted because every font preload competes with the largest contentful paint. The fallback faces use the Capsize metrics table for common fonts on their regular style; a family outside the table says so instead of inventing numbers. Overrides shrink the swap gap but do not remove layout shift entirely, and this tool is paste-only: fetching a stylesheet from a URL needs a server, because CORS blocks cross-origin reads in a browser tab.