Add optional BLE scan module for ESP32forth

[haywardt]

Summary

• Adds non-blocking BLE scanning words (ble-init, ble-scan-start, ble-scanning?, ble-scan-stop, ble-count, ble-addr, ble-rssi, ble-name, ble-new?, ble-forget) implemented in C++ via the ESP32 Arduino BLE library
• Provides both a direct-include header (esp32/ble-scan.h) for sketch use and a full optional module (esp32/optional/ble-scan/) wired into the optionals.fs boot sequence
• Marked very_optional (like serial-bluetooth) so it stays out of the bulk with_optional build, since BLE and WiFi can conflict

Test plan

• Copy ble-scan.h into an ESP32 Arduino sketch and verify it compiles
• Run: ble-init 5 ble-scan-start begin ble-scanning? while 100 ms repeat ble-count .
• Verify ble-addr, ble-rssi, ble-name, ble-new? return correct values for scanned devices
• Confirm ble-forget clears the seen history

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