Phase 3 / M3: Schedule exact-frame controls and per-note parameters #8

Objective

Route direct and note-local controls through the existing sample-accurate scheduler with deterministic ordering and stale-handle safety.

Scope

• Add EventSetControl/ControlCommand with symbolic target, generation, ownership epoch, sequence, and exact frame.
• Split render blocks at control frames and document/test same-frame ordering.
• Implement ctl, map form, scheduled form, control-value, controls, and reset-control!.
• Add play {:params ...} validation and apply values before a note's first rendered sample.
• Implement instrument/voice scope, inheritance, precedence, clamp opt-in, and future-event revalidation.
• Reject stale handles, NaN/Inf, range/scope errors, unknown controls, invalid times, and bounded-queue overflow with structured errors.
• Add control events/statistics and machine-readable control traces.

Acceptance criteria

• Controls apply at exact requested frames and produce block-size-invariant traces/audio.
• ctl changes audio without patch recompilation.
• Per-note values are present on the first sample, remain voice-independent, and stale handles cannot affect reused voices.

Spec: phase-3.md §§9–11, 15, 24–28, 31.1, 33–36, 40 (Milestone 3), 42.