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>

partitions.csv

@@ -0,0 +1,12 @@
+# ESP-IDF partition table: A/B OTA app slots + LittleFS storage.
+#
+# Sized for a 4MB flash module (TODO: adjust once real flash size and
+# firmware image size are known).
+#
+# Name,     Type, SubType,   Offset,   Size, Flags
+nvs,        data, nvs,       0x9000,   0x6000,
+otadata,    data, ota,       0xf000,   0x2000,
+phy_init,   data, phy,       0x11000,  0x1000,
+ota_0,      app,  ota_0,     0x20000,  0x180000,
+ota_1,      app,  ota_1,     0x1A0000, 0x180000,
+storage,    data, littlefs,  0x320000, 0xE0000,