Update dependencies and enhance README for RP2040 support

flake.nix

@@ -51,6 +51,10 @@
               cargo
               rustfmt
               rust-src
+              rust-std
+            ]
+            ++ [
+              targets.thumbv6m-none-eabi.latest.rust-std
             ]
           );
       };
@@ -75,9 +79,12 @@
               probe-rs-tools
               openocd
               minicom
+              cargo-binutils
+              flip-link
               # RP2040 UF2 workflows
               elf2uf2-rs
               picotool
+              tea
               pre-commit
             ];
 
@@ -101,7 +108,7 @@
                 rustup target add thumbv6m-none-eabi       >/dev/null 2>&1 || true  # Cortex-M0/M0+ (RP2040)
               fi
               echo "[rust-template] Welcome to the Rust dev shell!"
-              echo "Tools: cargo, rustc, clippy, rustfmt, rust-analyzer, probe-rs, openocd, minicom, elf2uf2-rs, picotool"
+              echo "Tools: cargo, rustc, clippy, rustfmt, rust-analyzer, probe-rs, openocd, minicom, elf2uf2-rs, picotool, cargo-binutils, flip-link, tea"
               echo "Run 'cargo build' to build, or 'nix run .#dev-helper' for a tool summary."
               echo "See README.md for usage."
             '';
@@ -118,6 +125,7 @@
             version = "0.1.0";
             src = ./.;
             cargoLock.lockFile = ./Cargo.lock;
+            meta.mainProgram = "rusty-dog";
           };
 
           devHelper = pkgs.writeShellScriptBin "dev-helper" ''