hotpath_init

Configure hotpath profiling in a Rust project. Adds the hotpath dependency with feature-gated setup, instruments main with hotpath::main, functions with measure/measure_all, and wraps channels, mutexes, rw_locks, streams, futures, reqwest clients, axum routers and byte-level I/O with hotpath macros. Use when the user wants to add or set up hotpath profiling in a crate.