cascade integration: sin-peak floor, complex twin resp storage, per-band cascade

- Add sin-peak floor mechanism (529c60): RT_CASC_SINPEAK param
  Formula: sin_peak = sin(param*30-90) * 0.115129 * peak_level
  Floor active for param in [3,9], max at param=6 (ln10/20=0.115129)
  Prevents over-reduction by clamping level curve from below

- Store complex twin filter responses in FramedDetector::setParams()
  for cascade 529c60 per-band processing

- Add cascade state persistence (fn529fe0::CascadeState per band)

- ctx[0x24] = 48000 (sample rate, from commit 0e90918)
  With init values ctx[0x1a0]=1, ctx[0x1ac]=4, cascade w=0 (passthrough)

- All tests pass: fn529fe0_check, render48k build OK

dsp/framed_model.hpp

@@ -2,6 +2,7 @@
 #include <cstddef>
 #include <complex>
 #include <vector>
+#include "fn529fe0.hpp"
 
 struct DetectorBand {
     float fc;    // band center freq (Hz)
@@ -71,6 +72,11 @@ public:
 
     void processFrame(const std::complex<double>* spectrum, float* mask);
 
+    // Cascade state access for per-band detector cascade
+    std::vector<fn529fe0::CascadeState>& cascadeStates() { return cascade_states_; }
+    const std::vector<std::vector<std::complex<double>>>& twinRespComplex() const { return twin_resp_complex_; }
+    std::vector<std::vector<std::complex<double>>>& twinRespComplex() { return twin_resp_complex_; }
+
 private:
     size_t nfft_;
     float sample_rate_;
@@ -82,4 +88,10 @@ private:
     std::vector<float> am_;                 // smoothed per-bin amplitude
     std::vector<float> f6f8_;               // shared 0x5406f8 blend buffer (IIR1 out)
     std::vector<std::vector<float>> track_; // per band, per bin accumulator 0x5407c8
+
+    // For cascade 529c60: per-band complex twin filter responses
+    std::vector<std::vector<std::complex<double>>> twin_resp_complex_;
+    
+    // Per-band cascade states
+    std::vector<fn529fe0::CascadeState> cascade_states_;
 };