Stash radio settings per app (#1151)

* add a little Stash utility.
* add radio state RAII helper.
* first part of radio_state changes
* add radio_state_ to rest of apps
* fix freq_step and format
* fix unused ui_sigfrx: corrected sample rate, added back freq setting

firmware/application/apps/ui_numbers.hpp

@@ -34,6 +34,7 @@
 #include "message.hpp"
 #include "file.hpp"
 #include "io_wave.hpp"
+#include "radio_state.hpp"
 
 namespace ui {
 
@@ -54,6 +55,11 @@ class NumbersStationView : public View {
    private:
     NavigationView& nav_;
 
+    TxRadioState radio_state_{
+        1750000 /* bandwidth */,
+        1536000 /* sampling rate */
+    };
+
     // Sequencing state machine
     enum segments {
         IDLE = 0,