Pin amy to ecfc04a80 (amy#1208)

[bwhitman]

⛓️ Pin amy → ecfc04a80 (validates shorepine/amy#1208)

amy was just merged to shorepine/amy@main. This PR bumps the amy submodule
pointer to that commit so the full tulipcc CI (AMYboard preview, Tulip preview, desktop
build) runs against it.

Please test, then merge this PR manually to move tulipcc onto the latest AMY.

Merged AMY PR	shorepine/amy#1208 — render_pcm: ramp the gain across the block
Author	@mateusz28011
Merged by	@dpwe
AMY commit	shorepine/amy@ecfc04a

What changed in this AMY PR

• 2e753e7 render_pcm: ramp the gain across the block

6 file(s) changed (+61/-3)

• amy/test.py (+44/-0)
• src/amy.c (+3/-1)
• src/pcm.c (+14/-2)
• tests/ref/TestBlueMonday.wav (+0/-0)
• tests/ref/TestPcmLoopEnvFilt.wav (+0/-0)
• tests/ref/TestPcmLoopForever.wav (+0/-0)

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cc @dpwe — you merged the AMY change above; please review the tulipcc CI on this PR and merge it here when green.

[github-actions]

🔌 AMYboard PR preview

Editor + flasher: https://amyboard-pr-1387.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-1387.vercel.app/run/

Flash a Tulip to this build: on-device run tulip.upgrade(pr=1387).

Rebuilt on every push; removed when the PR closes.

[github-actions]

🎛️ HW CI (physical bench)

AMYboard (USB-MIDI + AMY zP → audio; built-in tones + AMYboard World sketches acid/house/woodpiano over the SysEx control API): ✅ PASS — flashed this PR’s firmware; all checks matched the references.

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, the AMYboard World sketch refs (ref/{acid_generator,house_generator,woodpiano}.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.}