Minimal kesp32-app-base consumer

This example uses the repository's components/kesp32-app-base directly; it does not copy base sources.

source "$HOME/esp/esp-idf/export.sh"
idf.py -B build-minimal -D SDKCONFIG= sdkconfig set-target esp32
idf.py -B build-minimal build

A consumer supplies esp32_app_base_config_t and a product-start callback. Product partition tables and sdkconfig remain owned by the consumer.