feat(codemode): native coercion parity in interpreter

[rekram1-node]

Closes six coercion-parity gaps from interpreter-support.md where ordinary model-written JavaScript failed in CodeMode but works natively.

Changes

• String method argument coercion: "v1.2".includes(1), "abc".slice("1"), "a1b".replace(1, 2) coerce like native JS (including the callback-replacer path). Opaque runtime references still reject as data errors; includes/startsWith/endsWith reject regular expressions with a native-style TypeError; split(undefined) returns the whole string with zero limits honored.
• Zero-argument Number() and String() produce 0 and ""; Number(undefined) stays NaN.
• Global coercing isFinite/isNaN, usable as callbacks (values.filter(isFinite)).
• match()/matchAll()/search() with no argument behave as an empty pattern.
• ++/-- use CodeMode numeric coercion instead of host Number(...). This also fixes a real crash: x = {}; x++ previously surfaced a raw host TypeError because SafeObjects are null-prototype and host ToPrimitive throws. coerceToNumber now routes arrays through interpreter string coercion for the same reason ([{}] no longer leaks "No default value").
• Unknown static members read as undefined on global namespaces and the coercion functions, so feature detection (typeof Math.sumPrecise, Object.groupBy === undefined) works like native JS. Reads are gated on the same known-member sets the invoke switches use; calling an undefined value reports a native-style TypeError naming the callee (Math.sumPrecise is not a function.). Blocked members (constructor, __proto__, ...) still throw, and unknown Promise statics keep their descriptive error.

Deliberate documented deviations kept: repeat still requires a finite non-negative count (now branded RangeError), match/search arguments must still be a regex or string pattern, and opaque runtime references reject everywhere coercion happens.

Testing

• ~45 new direct behavior tests in test/parity.test.ts, with odd edges (split(undefined, 0), padStart("3", 0), "abc".match().index) cross-checked against native JS.
• 910 tests pass from packages/codemode; typecheck clean.
• interpreter-support.md checklist updated in the same PR.