Remove button mapping

source/config.h

@@ -56,8 +56,12 @@
 #define CONFIG_FILENAME  "/imu_mouse_cfg.bin"
 #define CONFIG_MAGIC     0xDEAD123EUL
 
-// Physical button sentinel 
-#define BTN_PIN_NONE  0xFF   // Stored in btn*Pin when that button is disabled
+// Physical button pin assignments (hardcoded - set to 0xFF to disable a button)
+// Valid pin numbers: 0-10 (Arduino D0-D10 on XIAO nRF52840 Sense)
+#define BTN_PIN_NONE   0xFF
+#define BTN_LEFT_PIN   BTN_PIN_NONE   // e.g. 0 for D0
+#define BTN_RIGHT_PIN  BTN_PIN_NONE   // e.g. 1 for D1
+#define BTN_MIDDLE_PIN BTN_PIN_NONE   // e.g. 2 for D2
 
 // Runtime feature-override flags (cfg.featureFlags bitmask) 
 // These mirror the compile-time FEATURE_* defines but can be toggled at runtime
@@ -98,9 +102,6 @@ struct Config {
   float      jerkThreshold;    // jerk² threshold for tap-freeze detection
   uint8_t    tapFreezeEnabled; // 1 = enable jerk-based cursor freeze during taps
   uint8_t    featureFlags;     // bitmask of FLAG_* - runtime feature overrides
-  uint8_t    btnLeftPin;       // BTN_PIN_NONE or Arduino pin number (0-10 = D0-D10)
-  uint8_t    btnRightPin;
-  uint8_t    btnMiddlePin;
 };
 extern Config cfg;
 extern const Config CFG_DEFAULTS;
@@ -120,11 +121,8 @@ struct __attribute__((packed)) ConfigBlob {
   uint8_t tapFreezeEnabled;  // [19]  1 = enable jerk-based cursor freeze during taps
   float   jerkThreshold;     // [20]  jerk² tap-freeze threshold
   uint8_t featureFlags;      // [24]  FLAG_* bitmask - runtime feature overrides
-  uint8_t btnLeftPin;        // [25]  BTN_PIN_NONE or Arduino pin (0-10 = D0-D10)
-  uint8_t btnRightPin;       // [26]
-  uint8_t btnMiddlePin;      // [27]
 };
-static_assert(sizeof(ConfigBlob) == 28, "ConfigBlob must be 28 bytes");
+static_assert(sizeof(ConfigBlob) == 25, "ConfigBlob must be 25 bytes");
 
 // TelemetryPacket (24 bytes) 
 #ifdef FEATURE_TELEMETRY