tauri-runtime-servocat 2.0.0

Servo-replacement runtime for Tauri: wires html-cat, css-cat, dom-cat, layout-cat, paint-cat, net-cat, boa-cat, ecma-runtime-cat, and web-api-cat into a single rendering + scripting pipeline. v2.0.0 visually applies the webview's tracked `background_color` (the softbuffer compositor now blends over the chosen colour instead of always white) and attaches the webview's cookie jar to net-cat HTTP requests during `navigate(http://...)` (as a single `Cookie: name=value; ...` header). The Servo no-AI policy disqualifies upstream contribution; this is the AI-built parallel.