[preview] Pin amy to MIDI running-status fix (amy#748) for testing

[bwhitman]

Preview PR — not for merge

Pins the amy submodule to shorepine/amy@694cb22, the head of shorepine/amy#748, so the MIDI running-status fix can be built and tested before that PR merges.

What this fixes

amy#748 fixes MIDI running status being broken whenever a System Real-Time byte (clock 0xF8, active sensing 0xFE, start/stop, …) is interleaved into the stream. A Novation Circuit Tracks uses running status and streams clock at 24 ppqn while playing, so every clock byte clobbered the stored note-on status and the following running-status note was silently dropped (shorepine/amy#747).

Submodule bump

amy: ff59eb2 → 694cb22. Besides the MIDI fix, the only commits pulled in are the AMYboard hardware-CI trigger infra (CI workflows, no runtime effect) and a doc typo fix — so functionally this is just the running-status fix.

How to test

git fetch origin
git checkout amy-pr-748-preview
git submodule update --init --recursive amy
# then build the web REPL / tulip / AMYboard firmware as usual

The pinned commit lives on the amy PR branch, so submodule update fetches it from shorepine/amy directly.

Before merge

Do not merge until amy#748 lands. Once it does, repoint amy at the merge commit on amy main instead of the PR-branch commit.

🤖 Generated with Claude Code

[github-actions]

🔌 AMYboard PR preview

Editor + flasher: https://amyboard-pr-1023.vercel.app/editor/

This preview bundles this PR's firmware — its flasher only flashes this build (not the release). Rebuilt on every push; removed when the PR closes.

The hardware CI has been kicked off and should return within a few minutes, stand by!

[github-actions]

🌷 Tulip Web PR preview

Tulip Web: https://tulip-pr-1023.vercel.app/run/

Flash a Tulip to this build: on-device run tulip.upgrade(pr=1023).

Rebuilt on every push; removed when the PR closes.

[github-actions]

🎛️ HW CI (physical bench)

AMYboard (USB-MIDI + AMY zP → audio): ❌ FAIL — a check did not match, or the run errored. See the log/artifacts.

Tulip (TULIP4_R11; serial-REPL audio + WiFi screenshot): ✅ PASS — flashed this PR’s firmware; all checks matched the references.

⬇️ Artifacts: recordings · screenshot · serial logs · run logs

_{Self-hosted bench. Audio spectral-compared to ref/hwci_basic.wav + ref/tulip_basic.wav; Tulip screenshot pixel-compared to ref/tulip_screenshot.png. Both analog outs share one capture card, so the tests run sequentially.}