Fix BLE crash: move all NimBLE calls to Core 0

Root cause: Arduino Core 3.x breaks cross-core NimBLE API calls.
Calling BLEMidiServer.controlChange() from loop() on Core 1 while
NimBLE host runs on Core 0 causes immediate crash.

Fix:
- Move ble_midi_transport.begin() to ble_init_task on Core 0
- All BLE MIDI sends use queue_cc() (cross-core safe flag setter)
- ble_midi_transport.update() processes queued sends on Core 0
- Pin NimBLE-Arduino to v1.4.3 (stable LTS for BLE MIDI)
- Keep CONFIG_BT_ENABLED out of sdkconfig.h (causes double-init)

include/ble_midi_transport.h

@@ -20,6 +20,8 @@ public:
 
     bool is_connected();
 
+    void queue_cc(uint8_t channel, uint8_t cc, uint8_t value);
+
 private:
     static void on_control_change(uint8_t channel, uint8_t controller, uint8_t value, uint16_t timestamp);
     static void on_note_on(uint8_t channel, uint8_t note, uint8_t velocity, uint16_t timestamp);
@@ -30,4 +32,9 @@ private:
     std::function<void(const MidiEvent&)> receive_callback;
     bool initialized;
     bool client_connected;
+
+    uint8_t queued_channel;
+    uint8_t queued_cc;
+    uint8_t queued_value;
+    bool   queued;
 };