feat(fm): add universal FM RAW decoder output

RadioModes.pas

@@ -0,0 +1,30 @@
+unit RadioModes;
+
+{$mode objfpc}{$H+}
+
+// Canonical persisted mode indices. Append only: these values are stored in
+// settings.json/channels.json and are exposed through CAT and the web API.
+interface
+
+const
+  MODE_LSB   = 0;
+  MODE_USB   = 1;
+  MODE_DSB   = 2;
+  MODE_CWL   = 3;
+  MODE_CWU   = 4;
+  MODE_FM    = 5;
+  MODE_AM    = 6;
+  MODE_SAM   = 7;
+  MODE_DIGU  = 8;
+  MODE_DIGL  = 9;
+  MODE_WFM   = 10;
+  MODE_DMR   = 11;
+  MODE_FMRAW = 12;
+
+  MODE_MIN   = MODE_LSB;
+  MODE_MAX   = MODE_FMRAW;
+  MODE_COUNT = MODE_MAX - MODE_MIN + 1;
+
+implementation
+
+end.