refactor(sinktools): remove sinktools

[MingweiSamuel]

The new dfir_pipes trait subsumes most of the short-lived sinktools crate's functionality. Some usage remains:

This crate is deeply integrated across the workspace. Let me give a clear summary of the dependencies:

The sinktools crate is used by 4 other crates with actual source code dependencies (not just changelogs):

1. dfir_rs (core runtime)

• Re-exports sinktools as a public dependency in src/lib.rs
• Uses sinktools::for_each in src/util/simulation.rs

2. hydro_lang (language/compiler)

• Uses sinktools::demux_map_lazy::LazyDemuxSink, sinktools::lazy::{LazySink, LazySource}, sinktools::lazy_sink_source::LazySinkSource in deploy runtime files
• Uses sinktools::map(...) in deploy runtime code generation (via q!() macros)
• Uses sinktools::demux_map_lazy::<_, _, _, _>(...) in containerized deploy code gen
• Uses __root_dfir_rs::sinktools::for_each(...) in compiled embedded output (compile/embedded.rs)
• Uses sinktools::lazy::LazySink in deploy graph containerized

3. hydro_deploy_integration

• Uses sinktools::demux_map::DemuxMap type alias for BufferedDrain
• Uses sinktools::demux_map(...) to create demuxers for connected sinks

4. benches

• Uses dfir_rs::sinktools::{SinkBuild, SinkBuilder, ToSinkBuild, for_each} in arithmetic, identity, and reachability benchmarks

This crate cannot be removed. It provides fundamental sink adaptor infrastructure (for_each, map, demux_map, demux_map_lazy, lazy sink/source, lazy_sink_source, SinkBuild/SinkBuilder) that is deeply woven into:

• The core DFIR runtime's output handling
• The Hydro language compiler's code generation for sink outputs
• The deployment infrastructure's demuxing of connections
• Performance benchmarks

Removing it would require either rewriting all this functionality inline into each consuming crate or finding an equivalent external crate — neither of which is a simple removal.