Add initial project structure and implement async main for Pico W

Makefile

@@ -1,14 +1,21 @@
+DIRENV := $(shell command -v direnv 2> /dev/null)
+ifdef DIRENV
+    EXEC := direnv exec .
+else
+    EXEC :=
+endif
+
 build:
-	cargo build
+	$(EXEC) cargo build
 
 run:
-	cargo run
+	$(EXEC) cargo run
 
 test:
-	cargo test
+	$(EXEC) cargo test
 
 clean:
-	cargo clean
+	$(EXEC) cargo clean
 
 .PHONY: build run test clean
 
@@ -16,4 +23,4 @@ clean:
 # Flatpak build target
 .PHONY: flatpak-build
 flatpak-build:
-	flatpak-builder --force-clean build-flatpak flatpak/app.flatpak.json
+	$(EXEC) flatpak-builder --force-clean build-flatpak flatpak/app.flatpak.json

README.md

@@ -2,6 +2,18 @@
 
 This project is an embedded Rust application for the Raspberry Pi Pico W, utilizing the Embassy async framework.
 
+## Build Commands
+
+This project uses a `Makefile` to simplify common tasks. The `Makefile` is configured to automatically use `direnv` to load the Nix environment if `direnv` is installed on your system. This ensures that the correct Rust toolchain and dependencies are available even if you haven't manually run `nix develop` or `direnv allow`.
+
+| Command | Description |
+|---------|-------------|
+| `make build` | Build the project using `cargo build` |
+| `make run` | Run the project using `cargo run` |
+| `make test` | Run tests using `cargo test` |
+| `make clean` | Clean build artifacts |
+| `make flatpak-build` | Build the Flatpak package |
+
 ## LLM Agent Guidelines
 
 This project uses LLM agents for configuration and housekeeping. Please refer to [agents.md](agents.md) for the rules and guidelines governing their use.