v0.9.3 — The PSP arena no longer strands the memory a QuickJS boot needs

The PSP arena no longer strands the memory a QuickJS boot needs.
A guest whose boot parses a megabyte of JSON could exhaust the heap while
megabytes sat free, because the arena's power-of-two size classes never hand a
block to a different class. 0.9.3 closes that, and
Pocket Voxel boots on a real
PSP-2000 at the default arena size again.

• realloc keeps the pointer when the new size stays inside the block's
  class. The arena rounds every request up to a power of two, so a grow that
  stays in class already owns those bytes. QuickJS grows its string and array
  builders geometrically, and the previous allocator answered every one of those
  grows with an allocate, a copy, and a free that put the old block into a class
  nothing asked for again. A boot parsing 1.15 MB of game data stranded
  megabytes this way.
• arena::alloc splits a larger free block when the bump is spent, halving
  down to the class it needs. It runs last on purpose: a heap with room behaves
  exactly as it did in 0.9.2, and large blocks stay whole for the callers that
  want them.
• A null exception object is an out-of-memory signature. [PocketJS js error] null followed by JS_Eval threw means QuickJS could not allocate an
  Error to throw, so the guest source is not the suspect. The same halt line
  covers every eval failure, which is what made this one read as a code bug for
  a day.
• globalThis.audio mounts without the ui surface. register_audio is
  split out of register, so a host that owns its own surface can still offer
  the audio.pcm capability. The credit mirror also decays with the hardware
  stream: poll() never subtracted what write() accepted, so a ring the mixer
  drained completely between two polls sent no credit and the guest went
  permanently silent after a couple of seconds.

Measured on the hardware that found it. The same guest bundle peaks at
12.3 MB under desktop QuickJS and needed more than 15.5 MB on the device
before this release; it now boots inside the 14.3 MB an XMB launch leaves
after a 32 MB pak, with the emulator journey green at 11 of 11 marks and
frame-hash goldens byte-identical at both quality rungs.

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npm: @pocketjs/framework@0.9.3 · @pocketjs/cli@0.9.3 · full changelog