feat(esp32-ui): add ESP32 UI firmware base structure

- Add Slint-based ESP32 UI firmware project
- Support ESP32-S3 and ESP32-C3 targets
- Include ST7789 display driver support
- Add touch controller support (XPT2046, FT6X36)
- Include pin configuration and hardware requirements
- Add build scripts and cargo configuration

Co-authored-by: ZeroClaw Agent <zeroclaw_agent@zeroclaw.local>

firmware/zeroclaw-esp32-ui/.cargo/config.toml

@@ -0,0 +1,13 @@
+[build]
+target = "riscv32imc-esp-espidf"
+
+[target.riscv32imc-esp-espidf]
+linker = "ldproxy"
+rustflags = [
+    "--cfg", 'espidf_time64',
+    "-C", "default-linker-libraries",
+]
+
+[unstable]
+build-std = ["std", "panic_abort"]
+build-std-features = ["panic_immediate_abort"]