Board Support Package for ssh-stamp-esp32.

Board definitions live in boards/*.toml (one file per board, containing pin mappings and an optional documentation URL). The build.rs reads those TOML files and generates all Rust code — board structs, the [take_uart_pins!] macro, and the [select_board!] macro — into OUT_DIR/boards_gen.rs, which is included here.

The TOML files are the single source of truth for pin numbers. No human writes or edits the generated Rust code.

Adding a board

1. Create boards/{board-name}.toml with a [pins] section (uart_rx and uart_tx, plus can_tx/can_rx and i2c_sda/i2c_scl for the buses the board breaks out), a [build] section naming its chip, and an optional url.
2. Add board-{name} = [] to [features] in Cargo.toml.

No .rs file, no macro editing, no binary changes. The build.rs validates that selected features have matching TOML files, and the board shows up in the catalog above on the next cargo xtask <board> doc.