[feat](trx-rds,trx-frontend-http): reset rds on tune changes

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/decoders/trx-rds/src/lib.rs

@@ -294,6 +294,7 @@ impl Candidate {
 
 #[derive(Debug, Clone)]
 pub struct RdsDecoder {
+    sample_rate_hz: u32,
     carrier_phase: f32,
     carrier_inc: f32,
     i_lp: OnePoleLowPass,
@@ -314,6 +315,7 @@ impl RdsDecoder {
             ));
         }
         Self {
+            sample_rate_hz: sample_rate.max(1),
             carrier_phase: 0.0,
             carrier_inc: TAU * RDS_SUBCARRIER_HZ / sample_rate_f,
             i_lp: OnePoleLowPass::new(sample_rate_f, 3_000.0),
@@ -343,6 +345,10 @@ impl RdsDecoder {
         self.best_state.as_ref()
     }
 
+    pub fn reset(&mut self) {
+        *self = Self::new(self.sample_rate_hz);
+    }
+
     pub fn snapshot(&self) -> Option<RdsData> {
         self.best_state.clone()
     }