Rebuild firmware scaffold for ESP32-C6/ESP-IDF, replacing NCS/Zephyr

The product pivoted away from a Matter-first nRF54L15 device to an
ESP32-C6/ESP-IDF/C++17 platform where behaviour is defined by a
Blockly-generated Lua program instead of custom firmware (see the
updated kvida meta-repo vision). Removes the west/NCS/Zephyr scaffold
and replaces it with:

- A pinned ESP-IDF v6.0.2 Docker build environment (Espressif's
  official image already bundles the toolchain, unlike NCS/west).
- A layered component structure (drivers -> sensors -> profiles ->
  lua_runtime -> transport) matching the new architecture principles,
  with per-component READMEs describing responsibilities.
- An A/B OTA + LittleFS partition table and a minimal main.cpp.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -1,18 +1,13 @@
-# Zephyr / nRF Connect SDK
+# ESP-IDF
 /build/
-/.west/
-/bootloader/
-/modules/
-/nrf/
-/nrfxlib/
-/zephyr/
-/tools/
+/managed_components/
+/dependencies.lock
+sdkconfig
+sdkconfig.old
 *.o
 *.elf
-*.hex
 *.bin
 *.map
-*.uf2
 
 # Python
 __pycache__/