ESP-IDF Build Entrypoint

Authoritative ESP build entrypoint.

Build authority:

ESP / ESP32-P4 -> ESP-IDF

Removed historical component root:

esp_idf implementation root

Final wrapper direction:

builds/esp_idf
  -> invokes apps/esp32_lvgl app shell

This directory now owns the migrated ESP-IDF source list and target defaults introduced in Batch 2:

ESP_IDF_COMPONENT_SOURCES.cmake
targets/tab5/sdkconfig.defaults
targets/tdisplayp4_tft/sdkconfig.defaults
targets/tdisplayp4_amoled/sdkconfig.defaults

Root legacy source has been removed. Any future physical ESP-IDF idf_component_register owner must live under final build/app/platform ownership, not under a restored historical source root.

Rules:

thin wrapper only
Build Entrypoint invokes
App Shell composes
do not assemble Chat/Map/GPS runtime here
do not choose UX pack here
do not define board facts here
do not invent target defaults that are not backed by repository evidence