Add audio nodes to the patch bay

Also make the patch bay responsive.

crates/synth-core/src/oscillator.rs

@@ -4,6 +4,7 @@
 //! Uses phase accumulation; bandlimited variants (BLEP/BLAMP) to follow.
 
 use crate::{AudioProcessor, CVProcessor, config::SampleRate};
+use crate::descriptor::{ComponentDescriptor, Direction, JackDescriptor, ParamDescriptor, SignalKind};
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum Waveform {
@@ -26,6 +27,19 @@ impl Vco {
         Self { waveform, freq_hz, phase: 0.0, sample_rate }
     }
 
+    pub const DESCRIPTOR: ComponentDescriptor = ComponentDescriptor {
+        kind: "vco",
+        label: "VCO",
+        jacks: &[
+            JackDescriptor { id: "cv_in",    label: "CV",  direction: Direction::Input,  signal: SignalKind::Cv    },
+            JackDescriptor { id: "audio_out", label: "Out", direction: Direction::Output, signal: SignalKind::Audio },
+        ],
+        params: &[
+            ParamDescriptor { id: "freq_hz",  label: "Freq", min: 20.0, max: 20_000.0, default: 440.0, unit: "Hz" },
+            ParamDescriptor { id: "waveform", label: "Wave", min: 0.0,  max: 4.0,      default: 1.0,   unit: ""   },
+        ],
+    };
+
     #[inline]
     fn next_sample(&mut self) -> f32 {
         let p = self.phase;