chore: land janitor round 1 and graft integration

Round 1 findings and fixes, all previously uncommitted:
- FXProcessor per-slot DSP history repair (HEAD does not compile without it)
- SynthVoice::getModulationValue, editor control-lock guard
- ExactCompare.h naming the deliberate exact float comparisons
- KnobLookAndFeel replacing the never-installed SerumLookAndFeel
- 55 first-party compiler warnings to 0
- AGENT.md renamed to AGENTS.md across Source/
- graft repository context graph and its hooks
- JANITOR_TASKS.md and UI_UX_AUDIT.md records

Source/SynthVoice.cpp

@@ -17,7 +17,7 @@ void SynthVoice::prepare (double sampleRate, int maxBlockSize)
     oscB.prepare (sampleRate);
     sub.prepare (sampleRate);
     noise.prepare (sampleRate);
-    filters.prepare (sampleRate, maxBlockSize);
+    filters.prepare (sampleRate);
     for (auto& e : env)
         e.prepare (sampleRate);
     scratch.setSize (2, maxBlockSize, false, false, true);
@@ -55,7 +55,7 @@ void SynthVoice::noteOn (int noteNumber, float velocity01, double freqHz, juce::
     juce::Random rng (noteSeed);
     noteRandom = rng.nextFloat();
 
-    sub.noteOn (freqHz, -1);
+    sub.noteOn();
     noise.noteOn (noteSeed);
 
     for (auto& e : env)
@@ -71,8 +71,20 @@ void SynthVoice::noteOff()
         e.noteOff();
 }
 
+float SynthVoice::getModulationValue (ModSource source) const noexcept
+{
+    if (source >= ModSource::Env1 && source <= ModSource::Env4)
+        return env[(size_t) ((int) source - (int) ModSource::Env1)].getValue();
+    if (source == ModSource::Velocity) return velocity;
+    if (source == ModSource::Note) return clampF ((float) note / 127.0f, 0.0f, 1.0f);
+    if (source == ModSource::Random) return noteRandom;
+    return 0.0f;
+}
+
 void SynthVoice::render (float* outL, float* outR, int numSamples, const RenderContext& ctx) noexcept
 {
+    jassert (numSamples <= scratch.getNumSamples());
+
     if (! active || numSamples <= 0)
         return;
 
@@ -118,14 +130,14 @@ void SynthVoice::render (float* outL, float* outR, int numSamples, const RenderC
             float v = src[(int) c.source];
             if (c.bipolar && ! isBipolarSource (c.source))
                 v = v * 2.0f - 1.0f;
-            mod[(int) c.target] += v * c.depth;
+            mod[(size_t) c.target] += v * c.depth;
         }
     }
     if (ctx.macros != nullptr)
     {
         for (int m = 0; m < kNumMacros; ++m)
             for (const auto& a : ctx.macros->assignments[(size_t) m])
-                mod[(int) a.target] += ctx.macroValues[m] * a.depth;
+                mod[(size_t) a.target] += ctx.macroValues[m] * a.depth;
     }
 
     // 5. Modulated oscillator parameters.
@@ -157,8 +169,8 @@ void SynthVoice::render (float* outL, float* outR, int numSamples, const RenderC
     // without resetting existing phases when modulated at control rate.
     if (oscillatorsNeedNoteOn)
     {
-        oscA.noteOn (freqA, a, seed);
-        oscB.noteOn (freqB, b, seed + 1);
+        oscA.noteOn (a, seed);
+        oscB.noteOn (b, seed + 1);
         oscillatorsNeedNoteOn = false;
     }
     else