fix: enable RLCD battery sensing by default

[openbrt]

Summary

• treat production WeClawBot sources as battery-equipped by default
• enable CONFIG_WEC_BATTERY_INSTALLED in public RLCD release defaults and fallback config
• bump firmware to 0.1.93 and document RLCD battery validation

Verification

• python3 scripts/check_firmware_regressions.py
• git diff --check
• ESP-IDF 5.5.2 public builds: Waveshare RLCD build-waveshare-v0193, Note 4 build-note4-v0193
• flashed both USB real devices preserving NVS; WEC:GET reports version 0.1.93
• RLCD power event: present=true, percent=62, voltage=3.81, usb_host_connected=true, external_power_connected=true
• Note 4 power event: present=true, percent=69, voltage=3.85, usb_host_connected=true, external_power_connected=true