[Copilot]

Forced synchronous TurboFan compilation makes Envoy wasm tests slow, especially under sanitizers. This adds a runtime Liftoff opt-in without changing production or wee8_compile_tool defaults.

• Registry: .envoy.1 plus v8-liftoff-option.patch, applied last; existing patches and source integrity unchanged.
• API: createV8Vm(V8Options options = {}) selects Liftoff with background tier-up disabled. Clones retain the options.
• Process scope: V8 flags are initialized once; the first engine initialization determines compiler selection for subsequent VMs.

proxy_wasm::V8Options options;
options.liftoff = true;
auto vm = proxy_wasm::createV8Vm(options);

Context: envoyproxy/envoy#48681.