js-invoke-method now branches on (number? recv) and (boolean? recv) before
falling through to the generic dict/fn path. js-invoke-number-method handles
toString (incl. radix 2-36), toFixed, valueOf, toLocaleString, toPrecision,
toExponential. js-invoke-boolean-method handles toString and valueOf.
Numbers had no .toString() on bare values before — (5).toString() crashed
with 'TypeError: toString is not a function'. This is one of the bigger
scoreboard misses on built-ins/Number category.
10 new unit tests, 469/471 total.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>