Γ-W1-T2 review: one restart funnel, tighter ceiling proof, effective-gain meter

Fold setLimiterEnabled's restart request into setInstrumentParams so every writer
keeps the host's latency report in sync. Pin the window-sizing identity, drop the
per-sample modulo, tighten the ceiling tolerance, publish the blended gain.

src/shell/instrument/reasampler_processor.h

@@ -232,9 +232,10 @@ public:
     void setMasterGainLinear(double linear);  // clamped to [0, masterGainMaxLinear()]
 
     // The master-bus limiter's single enable (persisted in the parameter set). UI thread only:
-    // the setter requests the host's kLatencyChanged restart, which the SDK requires be issued
-    // from the UI thread and which process() must therefore never trigger. Setting the value it
-    // already holds is a no-op, so repeated clicks on one segment cost no restart.
+    // a thin wrapper over setInstrumentParams, the one funnel that both mirrors the flag and
+    // requests the host's kLatencyChanged restart, which the SDK requires be issued from the UI
+    // thread and which process() must therefore never trigger. Setting the value it already
+    // holds is a no-op, so repeated clicks on one segment cost no restart.
     bool limiterEnabled() const {
         return limiterEnabled_.load(std::memory_order_relaxed);
     }