v1.1.2: Smooth HR variation, validation, and UI improvements

- Fix HR variation to use smooth sinusoidal algorithm instead of erratic jumps
- Clamp HR values to ±3 of target (was exceeding bounds)
- Add Pydantic Field validation for device values in API
- Add runtime BPM validation in MCP server
- Add battery slider control for HR monitor
- Add distance display and reset button for treadmill
- Add UI/API version display in header
- Firmware: web portal improvements, battery/distance controls

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

firmware/esp32_ble_sim/include/web_portal.h

@@ -23,8 +23,18 @@ struct PortalStatus {
     String ipAddress;
     String deviceType;
     bool bleStarted;
+    uint32_t treadmillDistance;
+    uint8_t batteryLevel;
 };
 
+// Callback for resetting treadmill distance
+typedef void (*ResetDistanceCallback)();
+void setResetDistanceCallback(ResetDistanceCallback callback);
+
+// Callback for setting battery level
+typedef void (*SetBatteryCallback)(uint8_t level);
+void setSetBatteryCallback(SetBatteryCallback callback);
+
 void updatePortalStatus(const PortalStatus& status);
 
 #endif // WEB_PORTAL_H