Gleam stops compiling to Erlang source, and builds get much faster

Gleam doesn't compile to Erlang source anymore

Gleam v1.19.0 rewrites its Erlang code generator to emit Erlang abstract forms instead of Erlang source, skipping the front half of the Erlang compiler. Build times drop sharply, and BEAM crash reports and stacktraces now point to accurate Gleam line numbers. The release also flattens JavaScript pattern matching, optimizes short list literals, and adds TypeScript overloads that preserve type parameters.