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>

main/CMakeLists.txt

@@ -0,0 +1,5 @@
+idf_component_register(
+    SRCS "main.cpp"
+    INCLUDE_DIRS "."
+    REQUIRES drivers sensors profiles transport lua_runtime
+)

main/main.cpp

@@ -0,0 +1,10 @@
+#include "esp_log.h"
+
+namespace {
+constexpr const char *TAG = "kvida_os";
+}
+
+extern "C" void app_main(void)
+{
+    ESP_LOGI(TAG, "kvida-os starting");
+}