chore: add BluetoothProxy manifest placeholder for web flasher

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: limengdu

docs/flasher/firmware/BluetoothProxy/manifest.json

@@ -0,0 +1,9 @@
+{"name":"BLE-MQTT Gateway","version":"1.0.0","new_install_prompt_erase":true,"builds":[
+{"chipFamily":"ESP32-C3","parts":[{"path":"C3/bootloader.bin","offset":0},{"path":"C3/partitions.bin","offset":32768},{"path":"C3/boot_app0.bin","offset":57344},{"path":"C3/firmware.bin","offset":65536}]}
+,
+{"chipFamily":"ESP32-C5","parts":[{"path":"C5/bootloader.bin","offset":0},{"path":"C5/partitions.bin","offset":32768},{"path":"C5/boot_app0.bin","offset":57344},{"path":"C5/firmware.bin","offset":65536}]}
+,
+{"chipFamily":"ESP32-C6","parts":[{"path":"C6/bootloader.bin","offset":0},{"path":"C6/partitions.bin","offset":32768},{"path":"C6/boot_app0.bin","offset":57344},{"path":"C6/firmware.bin","offset":65536}]}
+,
+{"chipFamily":"ESP32-S3","parts":[{"path":"S3/bootloader.bin","offset":0},{"path":"S3/partitions.bin","offset":32768},{"path":"S3/boot_app0.bin","offset":57344},{"path":"S3/firmware.bin","offset":65536}]}
+]}