Execute pending resets before loading Memory PCM

[mateusz28011]

Summary

• execute due AMY events before allocating a Memory PCM preset
• extend the existing TestLoadSample golden test to cover amy.reset()
  immediately followed by amy.load_sample()

Problem

amy.reset() queues RESET_ALL_OSCS, while Memory PCM allocation performed
by load_sample() happens immediately when the transfer header is parsed.

This allows the following ordering:

1. RESET_ALL_OSCS is queued
2. the new Memory PCM preset is allocated and loaded
3. the queued reset executes
4. amy_reset_oscs() calls pcm_unload_all_presets()
5. the newly loaded preset is removed

As a result, the same PCM note can produce different audio depending on when
the pending reset executes.

Patch loading already prevents the equivalent ordering race by calling
amy_execute_deltas() immediately before patches_load_patch() (#372).
This change applies the same ordering boundary immediately before pcm_load().

Only due events are executed; future scheduled events remain queued.

Regression test

The existing TestLoadSample golden test now resets AMY immediately before
loading its sample.

Before the fix:

TestLoadSample: signal=-27.1 dB err=-26.2 dB

After the fix:

TestLoadSample: signal=-33.7 dB err=-100.0 dB

The existing reference WAV does not change.

Test plan

• python3 -m amy.test quiet — 119 tests pass
• make check-c-api
• make web — not run locally because emcc is unavailable; covered by CI

[dpwe]

Thanks!

[bwhitman]

⛓️ tulipcc integration PR opened

This merge was pinned into tulipcc for full-system CI: shorepine/tulipcc#1228

Test it there and merge that PR to move tulipcc onto this AMY.