## String
- Constructor: String(), String.fromCharCode(), String.fromCodePoint()
- Prototype: charAt, charCodeAt, codePointAt, concat, slice, substring,
substr, indexOf, lastIndexOf, includes, startsWith, endsWith, trim,
trimStart, trimEnd, padStart, padEnd, repeat, split, replace,
replaceAll, toLowerCase, toUpperCase, at, toString, valueOf

## Number
- Constructor: Number()
- Static: isNaN, isFinite, isInteger, isSafeInteger, parseInt, parseFloat
- Constants: EPSILON, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, MAX_VALUE,
MIN_VALUE, NaN, POSITIVE_INFINITY, NEGATIVE_INFINITY
- Prototype: toString(radix), valueOf, toFixed, toPrecision, toExponential

## Boolean
- Constructor: Boolean() with truthiness coercion
- Prototype: toString, valueOf

## Symbol
- Factory: Symbol(description) producing unique string-based identifiers
- Well-known: Symbol.iterator, toPrimitive, toStringTag, hasInstance
- Registry: Symbol.for(key), Symbol.keyFor(sym)

## VM Changes
- Added string_prototype, number_prototype, boolean_prototype to Vm
- Primitive auto-boxing: GetProperty/GetPropertyByName now look up
prototype methods for String, Number, and Boolean values
- Global constants: NaN, Infinity, undefined

37 new tests (328 total JS tests, all passing)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- parseInt: default radix 0 (auto-detect) instead of 10, so "0xFF" works
- array_concat: use array_length_exists() to correctly spread empty arrays
- Remove unused obj_proto parameter from error constructor helpers

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Add comprehensive built-in object support for the JavaScript engine:

## Infrastructure
- NativeContext passed to native callbacks (GC access + this binding)
- Object.prototype and Array.prototype stored in VM
- CreateObject/CreateArray set prototype chains
- Array literals now set length property

## Object built-ins
- Constructor, Object.keys/values/entries/assign/create/is
- Object.getPrototypeOf/getOwnPropertyNames/getOwnPropertyDescriptor
- Object.defineProperty/freeze/seal/isFrozen/isSealed
- Object.fromEntries/hasOwn
- Object.prototype: hasOwnProperty/toString/valueOf

## Array built-ins
- Native: push/pop/shift/unshift, indexOf/lastIndexOf/includes
- Native: join/slice/concat/reverse/splice/fill/at/toString
- Static: Array.isArray/from/of
- JS preamble: map/filter/reduce/reduceRight/forEach
- JS preamble: find/findIndex/some/every/sort/flat/flatMap

## Error built-ins
- Error/TypeError/ReferenceError/SyntaxError/RangeError/URIError/EvalError
- Prototype chain with name/message, Error.prototype.toString

## Global functions
- parseInt/parseFloat/isNaN/isFinite

37 new tests covering all built-in categories.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>