v2.7.0 — Tone.js 15.1.22 upgrade

Upgrades the audio engine a full major version: Tone.js 14.9.17 → 15.1.22 (the pinned CDN dependency in public/index.html, URL + SRI hash bumped together).

Why it's a clean bump

v15.1.22 retains Tone.Transport / Tone.context / Tone.Destination as functional accessors with no deprecation warnings, so no changes were needed to public/audio/tone-engine.js despite heavy use of those globals.

Verification

Re-tested with a headless-Chrome A/B audio harness (raw CDP, master + drum-soloed capture, band-energy analysis in Node) across 9 genres:

• ✅ Nothing silent; identical net/track composition; no console errors or deprecation spam.
• ✅ No lost drums — drum bus (channels 10–15) soloed and compared v14↔v15: low-band energy and peak transients statistically identical across techno/house/dnb/funk/trap/dubstep.
• ✅ Full-mix RMS swings traced to capture-phase jitter (±100% within a single version), not synthesis regressions.
• ✅ go test ./... green.

Notes

Feed's cached .webm renders are first-write-wins, so existing feed audio is unchanged; new renders use v15 (sonically equivalent per the A/B).

🤖 Generated with Claude Code