Fix WASM memory view invalidation when memory grows

[justjake]

Summary

When Emscripten's WASM memory grows (due to -sALLOW_MEMORY_GROWTH), all existing TypedArray views become detached because the underlying ArrayBuffer is replaced. This caused bugs where reading from views after FFI calls returned undefined (in the C correctness sense) values if memory had grown during the call.

The fix introduces RefreshableTypedArray, a wrapper that lazily recreates the TypedArray view when HEAPU8.buffer changes. This uses a simple reference comparison that only triggers view recreation when actually needed.

Affected call sites:

• runtime.ts: executePendingJobs - reads ctxPtrOut after QTS_ExecutePendingJob
• context.ts: newPromise - reads resolve/reject handles after QTS_NewPromiseCapability
• context.ts: getLength - reads uint32Out after QTS_GetLength
• context.ts: getOwnPropertyNames - reads outPtr and uint32Out after QTS_GetOwnPropertyNames

Also fixed: getOwnPropertyNames was using HEAP8.buffer instead of HEAPU8.buffer

Fixes #240

Test plan

• All 69 existing tests pass
• Manual testing with memory-intensive workloads that trigger growth

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