[nosam1998]

Add numerical quality fixtures, maximum four-voice/10-second profiling, 32-entry soundboard listing and 100 trigger/Stop checks, automated accessibility/responsive checks, and actual Safari WebDriver coverage on macOS.

Use trapezoidal integration for sampled pitch/readhead modulation, avoid redundant modulator reconstruction, include export source tables in buffer estimates, and release unreferenced in-memory project assets. Tighten ZIP header validation. Add selected-model overlays and explicit modulator audition/numeric inspection.

Part of #2, #9, #12, #15, #16, #19, and #20. Validation at f14b36b: 35 unit tests, syntax/build, Chromium/Firefox/WebKit integrated flows, WCAG-tagged axe checks, responsive layout, and real Safari 26.6.2 on macOS 26.6.2 passed. Recovery tests cover corrupt project files, quota failures, decoder cancellation, stopped/obsolete playback, and immutable-source deletion.

CI evidence: 32 pads list with zero PCM reads; 100 prepared pad play/Stop cycles leave zero audio nodes and measure 8.4 ms p95. Max 10-second/four-voice/mix-varispeed rendering produces 480,000 frames, peaks ≤0.95, and sampled typed-buffer usage ≤42.94 MiB. Ten shared-runner runs measure 1.51–2.74 seconds; the proposed 2-second p95 target remains unmet and is retained as an explicit release qualification item in #16. Analysis p95 is 40.25 ms. No human usability/listening evidence is claimed.