v1.4.0: BLE disconnect simulation with teardown support

Features:
- Add BLE disconnect simulation to test client reconnection behavior
- Support immediate disconnect, timed advertising pause, and full BLE teardown
- Add preset test buttons in admin UI (Quick Drop, 5s Pause, BLE Restart, 10s Restart)
- Add simulate_ble_disconnect MCP tool with duration_ms and teardown params
- Add POST /devices/{id}/disconnect API endpoint

Fixes:
- Fix treadmill distance not updating in admin UI (publish values periodically)
- Fix HR variation sending to non-heart_rate devices
- Fix BLE connection ID 0 being treated as "not connected"
- Clean up misleading startup log messages

Firmware: 1.1.0, API: 1.4.0, UI: 1.5.0

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

firmware/esp32_ble_sim/include/config.h

@@ -4,7 +4,7 @@
 // ============================================
 // Firmware Version
 // ============================================
-#define FIRMWARE_VERSION "1.0.7"
+#define FIRMWARE_VERSION "1.1.0"
 
 // ============================================
 // AP Mode Configuration

firmware/esp32_ble_sim/include/services/ble_service.h

@@ -44,13 +44,23 @@ public:
     // State
     bool isClientConnected() const { return deviceConnected; }
 
+    // Disconnect simulation
+    void disconnectClient();                    // Force disconnect + immediate re-advertise
+    void disconnectClientForDuration(int ms);   // Disconnect + pause advertising for duration
+    void teardownForDuration(int ms);           // Full BLE deinit + reinit after duration
+
 private:
     BleService() = default;
 
     bool deviceConnected = false;
     unsigned long lastNotify = 0;
+    unsigned long advertisingResumeTime = 0;    // When to resume advertising (0 = not paused)
+    bool advertisingPaused = false;
+    unsigned long teardownResumeTime = 0;       // When to reinit BLE after teardown
+    bool teardownPending = false;
 
     void initBLE();
+    void reinitBLE();                           // Reinit BLE and restore services
 };
 
 #define bleService BleService::getInstance()