S12: store wall-clock ADSR/pitch-env as seconds, resolve to frames at live rate

Kill kTier0Nominal*, adsrNeedsRateResolve, tier0Adsr, gateAdsr. Zones payload v5 carries
seconds; v3 legacy reads convert at the frozen authoring rate; v4 (branch-only) dropped.
Editor sliders now seconds. Engine takes frames resolved at keymap build.

src/vst/sampler_core.h

@@ -341,18 +341,15 @@ public:
     // Starts this voice on `note` at `velocity`, playing `sample` (a stable reference
     // the caller must keep alive for the voice's lifetime — the Keymap owns it), repitched
     // from `rootNote`. All five AHDSR fields (A/H/D/S/R) are read directly from
-    // sample.play.adsr — the per-zone values stamped by buildTier0Keymap / buildZonedKeymap.
-    // `gateAdsr` is the VoiceEngine's instrument-wide ADSR parameter, accepted for interface
-    // compatibility but NOT used by start() (vestigial since the S12 review fix moved A/D/S/R
-    // onto the per-zone SampleData). The S15 play MODE + Trigger params and the S16 pitch
-    // ENGINE + pitch envelope are read from `sample.play`. The Preserve shifters MUST already
-    // be pre-sized (presizePreserveShifters, off-thread) — start() only reset()s + warm()s
-    // them (RT-safe, no allocation) since it runs on the audio thread inside process(). The warm
-    // silence pass settles the OLA taps before the first output frame (no cold-start click).
-    // Byte-identical to the pre-S15 engine when sample.play is default (Gate + Varispeed + no
-    // pitch env).
-    void start(int note, int velocity, const SampleData& sample, int rootNote,
-               const AdsrParams& gateAdsr);
+    // sample.play.adsr — the per-zone values (in FRAMES) resolved from the stored seconds by
+    // buildTier0Keymap / buildZonedKeymap against the live sample rate. The S15 play MODE +
+    // Trigger params and the S16 pitch ENGINE + pitch envelope are read from `sample.play`.
+    // The Preserve shifters MUST already be pre-sized (presizePreserveShifters, off-thread) —
+    // start() only reset()s + warm()s them (RT-safe, no allocation) since it runs on the audio
+    // thread inside process(). The warm silence pass settles the OLA taps before the first
+    // output frame (no cold-start click). Byte-identical to the pre-S15 engine when sample.play
+    // is default (Gate + Varispeed + no pitch env).
+    void start(int note, int velocity, const SampleData& sample, int rootNote);
 
     // Gate off — begins the amplitude release. In GATE mode this enters the AHDSR release; in
     // TRIGGER mode it is a NO-OP (Trigger ignores note-off and plays through to its play length).
@@ -456,18 +453,19 @@ class VoiceEngine {
 public:
     // Builds an engine with `maxVoices` voices (the polyphony bound) playing from
     // `keymap`. The keymap must outlive the engine (the engine holds a reference — it
-    // reads zones and sample data through it, never copies PCM). `adsr` is the instrument-wide
-    // Gate AHDSR timing (attack/decay/sustain/release); each zone's HOLD stage + play mode +
-    // pitch engine ride on its SampleData::play. `preserveVoiceCap` (S16) bounds how many
-    // Preserve-engine voices may sound at once (the shifter is materially heavier than
-    // Varispeed) — a Preserve note-on beyond the cap is dropped rather than glitching; 0 means
-    // "no separate Preserve cap" (bounded only by maxVoices). `preserveWindowFrames` is the OLA
-    // window (in OUTPUT frames) every voice's Preserve pitch shifters are PRE-SIZED to at
-    // construction (OFF the audio thread), so note-on (which runs in process()) never allocates;
-    // 0 leaves them pass-through (a Varispeed-only instrument pays no ring cost). The processor
-    // derives it from the host sample rate (kPreserveWindowMs). Defaulted so existing callers
-    // (and the pure-core tests) are unaffected.
-    VoiceEngine(std::size_t maxVoices, const Keymap& keymap, const AdsrParams& adsr,
+    // reads zones and sample data through it, never copies PCM). Every AHDSR field (A/H/D/S/R)
+    // + play mode + pitch engine rides on each zone's SampleData::play (in FRAMES, resolved
+    // from the stored seconds at keymap build); the engine holds no instrument-wide ADSR.
+    // `preserveVoiceCap` (S16) bounds how many Preserve-engine voices may sound at once (the
+    // shifter is materially heavier than Varispeed) — a Preserve note-on beyond the cap is
+    // dropped rather than glitching; 0 means "no separate Preserve cap" (bounded only by
+    // maxVoices). `preserveWindowFrames` is the OLA window (in OUTPUT frames) every voice's
+    // Preserve pitch shifters are PRE-SIZED to at construction (OFF the audio thread), so
+    // note-on (which runs in process()) never allocates; 0 leaves them pass-through (a
+    // Varispeed-only instrument pays no ring cost). The processor derives it from the host
+    // sample rate (kPreserveWindowMs). Defaulted so existing callers (and the pure-core tests)
+    // are unaffected.
+    VoiceEngine(std::size_t maxVoices, const Keymap& keymap,
                 std::size_t preserveVoiceCap = 0, std::int64_t preserveWindowFrames = 0);
 
     // MIDI note-on. Resolves the note+velocity to a zone; if none matches (out of
@@ -524,7 +522,6 @@ private:
 
     std::vector<Voice> voices_;
     const Keymap& keymap_;
-    AdsrParams adsr_;
     std::size_t preserveVoiceCap_ = 0;  // S16: max simultaneous Preserve voices (0 = no separate cap)
     std::uint64_t nextStartOrder_ = 1;  // monotonic; 0 reserved for "never started"
 };