Add MEDIUM_TURBO modem preset (#10988)

* Protobufs

* Wire up MEDIUM_TURBO modem preset

MEDIUM_TURBO (500 kHz, SF9, CR 4/5) already existed in the protobuf enum but
was never wired into firmware, so selecting it silently fell through to the
LONG_FAST default and rendered an "Invalid" display name.

Add its bw/sf/cr mapping (modemPresetToParams), display name (MediumTurbo/MedT),
PRESETS_STD membership (standard regions only — 500 kHz does not fit EU868's
250 kHz band, so it stays out of PRESETS_EU_868 and is rejected/clamped there),
and the MEDIUM SNR-grading bucket. Includes positive coverage in test_radio,
EU868-reject + US-accept coverage in test_admin_radio and test_mesh_beacon,
the STD preset count 9->10, an extended fuzz range, and the client-spec doc.

* Address review feedback on MEDIUM_TURBO tests

- test_mesh_beacon: assert has_mesh_beacon before checking the invalid preset was
  cleared, so the EU868-cleared test can't pass on a dropped message (matches the
  existing SHORT_TURBO test).
- test_fuzz_packets: draw modem presets from _ModemPreset_ARRAYSIZE instead of a
  hard-coded 17 so the fuzz range tracks future enum additions automatically.

src/DisplayFormatters.cpp

@@ -27,6 +27,9 @@ const char *DisplayFormatters::getModemPresetDisplayName(meshtastic_Config_LoRaC
     case PRESET(MEDIUM_FAST):
         return useShortName ? "MedF" : "MediumFast";
         break;
+    case PRESET(MEDIUM_TURBO):
+        return useShortName ? "MedT" : "MediumTurbo";
+        break;
     case PRESET(LONG_SLOW):
         return useShortName ? "LongS" : "LongSlow";
         break;

src/graphics/draw/UIRenderer.cpp

@@ -844,6 +844,7 @@ void UIRenderer::drawFavoriteNode(OLEDDisplay *display, OLEDDisplayUiState *stat
             return -6.0f;
         case PRESET(MEDIUM_SLOW):
         case PRESET(MEDIUM_FAST):
+        case PRESET(MEDIUM_TURBO):
             return -5.5f;
         case PRESET(SHORT_SLOW):
         case PRESET(SHORT_FAST):

src/mesh/MeshRadio.h

@@ -229,6 +229,11 @@ static inline void modemPresetToParams(meshtastic_Config_LoRaConfig_ModemPreset
         cr = 5;
         sf = 10;
         break;
+    case PRESET(MEDIUM_TURBO):
+        bwKHz = wideLora ? 1625.0f : 500.0f;
+        cr = 5;
+        sf = 9;
+        break;
     case PRESET(LONG_TURBO):
         bwKHz = wideLora ? 1625.0f : 500.0f;
         cr = 8;

src/mesh/RadioInterface.cpp

@@ -39,8 +39,8 @@
 #endif
 
 static const meshtastic_Config_LoRaConfig_ModemPreset PRESETS_STD[] = {
-    PRESET(LONG_FAST),  PRESET(LONG_SLOW),     PRESET(MEDIUM_SLOW), PRESET(MEDIUM_FAST), PRESET(SHORT_SLOW),
-    PRESET(SHORT_FAST), PRESET(LONG_MODERATE), PRESET(SHORT_TURBO), PRESET(LONG_TURBO),  MODEM_PRESET_END};
+    PRESET(LONG_FAST),     PRESET(LONG_SLOW),   PRESET(MEDIUM_SLOW), PRESET(MEDIUM_FAST),  PRESET(SHORT_SLOW), PRESET(SHORT_FAST),
+    PRESET(LONG_MODERATE), PRESET(SHORT_TURBO), PRESET(LONG_TURBO),  PRESET(MEDIUM_TURBO), MODEM_PRESET_END};
 
 static const meshtastic_Config_LoRaConfig_ModemPreset PRESETS_EU_868[] = {
     PRESET(LONG_FAST),  PRESET(LONG_SLOW),  PRESET(MEDIUM_SLOW),   PRESET(MEDIUM_FAST),

src/mesh/generated/meshtastic/config.pb.h

@@ -374,7 +374,11 @@ typedef enum _meshtastic_Config_LoRaConfig_ModemPreset {
  Note: TCXO with tight tolerances (±5 ppm or better) is *absolutely required* at these narrow bandwidths.
  Only compatible with SX127x and SX126x chipsets.
  Comparable link budget and data rate to LONG_MODERATE. */
-    meshtastic_Config_LoRaConfig_ModemPreset_TINY_SLOW = 15
+    meshtastic_Config_LoRaConfig_ModemPreset_TINY_SLOW = 15,
+    /* Medium Range - Turbo
+ This preset performs similarly to MEDIUM_FAST, but with 500kHz bandwidth.
+ It is not legal to use in all regions due to this wider bandwidth. */
+    meshtastic_Config_LoRaConfig_ModemPreset_MEDIUM_TURBO = 16
 } meshtastic_Config_LoRaConfig_ModemPreset;
 
 typedef enum _meshtastic_Config_LoRaConfig_FEM_LNA_Mode {
@@ -767,8 +771,8 @@ extern "C" {
 #define _meshtastic_Config_LoRaConfig_RegionCode_ARRAYSIZE ((meshtastic_Config_LoRaConfig_RegionCode)(meshtastic_Config_LoRaConfig_RegionCode_ITU2_125CM+1))
 
 #define _meshtastic_Config_LoRaConfig_ModemPreset_MIN meshtastic_Config_LoRaConfig_ModemPreset_LONG_FAST
-#define _meshtastic_Config_LoRaConfig_ModemPreset_MAX meshtastic_Config_LoRaConfig_ModemPreset_TINY_SLOW
-#define _meshtastic_Config_LoRaConfig_ModemPreset_ARRAYSIZE ((meshtastic_Config_LoRaConfig_ModemPreset)(meshtastic_Config_LoRaConfig_ModemPreset_TINY_SLOW+1))
+#define _meshtastic_Config_LoRaConfig_ModemPreset_MAX meshtastic_Config_LoRaConfig_ModemPreset_MEDIUM_TURBO
+#define _meshtastic_Config_LoRaConfig_ModemPreset_ARRAYSIZE ((meshtastic_Config_LoRaConfig_ModemPreset)(meshtastic_Config_LoRaConfig_ModemPreset_MEDIUM_TURBO+1))
 
 #define _meshtastic_Config_LoRaConfig_FEM_LNA_Mode_MIN meshtastic_Config_LoRaConfig_FEM_LNA_Mode_DISABLED
 #define _meshtastic_Config_LoRaConfig_FEM_LNA_Mode_MAX meshtastic_Config_LoRaConfig_FEM_LNA_Mode_NOT_PRESENT

src/modules/CannedMessageModule.cpp

@@ -2118,6 +2118,7 @@ static float getSnrLimit(meshtastic_Config_LoRaConfig_ModemPreset preset)
         return -6.0f;
     case PRESET(MEDIUM_SLOW):
     case PRESET(MEDIUM_FAST):
+    case PRESET(MEDIUM_TURBO):
         return -5.5f;
     case PRESET(SHORT_SLOW):
     case PRESET(SHORT_FAST):