temporal_rs needs float64_representable_durations for spec Durations

temporal_rs stores Duration fields as exact i128/i64 by default, so new Temporal.Duration(0,0,0,0,0,0,0,0,Number.MAX_SAFE_INTEGER,0).add({microseconds: Number.MAX_SAFE_INTEGER-1}).toString() gives PT18014398509.481981S instead of the spec's PT18014398509.48198S, and Duration.compare(r.add({microseconds:1}), r) returns 1 instead of 0. The spec requires float64-representable fields; temporal_rs has a cargo feature float64_representable_durations for this (issues #613/#621). temporal_capi does not forward it, so an embedder that only depends on temporal_capi (Deno's rusty_v8 enables only zoneinfo64) fails the 9 test262 */float64-representable-integer.js tests. Enable it with a direct temporal_rs dependency that sets the feature (Cargo unifies features).