Add configuration slider for double tapping

source/config.h

@@ -60,6 +60,16 @@ enum CurveType   : uint8_t { CURVE_LINEAR=0, CURVE_SQUARE=1, CURVE_SQRT=2 };
 enum ChargeMode  : uint8_t { CHARGE_OFF=0,   CHARGE_SLOW=1,  CHARGE_FAST=2 };
 enum ChargeStatus: uint8_t { CHGSTAT_DISCHARGING=0, CHGSTAT_CHARGING=1, CHGSTAT_FULL=2 };
 
+// ─── Tap action types ─────────────────────────────────────────────────────────
+// TAP_ACTION_KEY: fires a raw HID keycode (tapKey) with optional modifier (tapMod).
+// Modifier byte: bit0=Ctrl, bit1=Shift, bit2=Alt, bit3=GUI (same as HID modifier byte).
+enum TapAction : uint8_t {
+  TAP_ACTION_LEFT   = 0,
+  TAP_ACTION_RIGHT  = 1,
+  TAP_ACTION_MIDDLE = 2,
+  TAP_ACTION_KEY    = 3,
+};
+
 // ─── Config (stored in flash) ─────────────────────────────────────────────────
 struct Config {
   uint32_t   magic;
@@ -69,11 +79,15 @@ struct Config {
   CurveType  curve;
   uint8_t    axisFlip;
   ChargeMode chargeMode;
+  uint8_t    tapThreshold; // 1–31 → REG_TAP_THS_6D bits[4:0]; 1 LSB = 62.5 mg at ±2g
+  TapAction  tapAction;    // what a double-tap does
+  uint8_t    tapKey;       // HID keycode (used when tapAction == TAP_ACTION_KEY)
+  uint8_t    tapMod;       // HID modifier byte (used when tapAction == TAP_ACTION_KEY)
 };
 extern Config cfg;
 extern const Config CFG_DEFAULTS;
 
-// ─── ConfigBlob (over BLE, 16 bytes) ─────────────────────────────────────────
+// ─── ConfigBlob (over BLE, 20 bytes) ─────────────────────────────────────────
 struct __attribute__((packed)) ConfigBlob {
   float   sensitivity;    // [0]
   float   deadZone;       // [4]
@@ -81,9 +95,13 @@ struct __attribute__((packed)) ConfigBlob {
   uint8_t curve;          // [12]
   uint8_t axisFlip;       // [13]
   uint8_t chargeMode;     // [14]
-  uint8_t _pad;           // [15]
+  uint8_t tapThreshold;   // [15]  1–31
+  uint8_t tapAction;      // [16]  TapAction enum
+  uint8_t tapKey;         // [17]  HID keycode
+  uint8_t tapMod;         // [18]  HID modifier
+  uint8_t _pad;           // [19]
 };
-static_assert(sizeof(ConfigBlob) == 16, "ConfigBlob must be 16 bytes");
+static_assert(sizeof(ConfigBlob) == 20, "ConfigBlob must be 20 bytes");
 
 // ─── TelemetryPacket (24 bytes) ───────────────────────────────────────────────
 #ifdef FEATURE_TELEMETRY