🔖 Add obipipeline parallel pipeline library

- Introduce `obipipline` crate with multi-threaded data pipeline architecture
- Implement core types: SourceFn, SharedFun (Arc), SinkFN with biased scheduler and crossbeam channels
- Add macros: `make_source!`, `transform!/fallible`/sink!, and high-level DSL macro
- Replace old wrapper/error modules with unified scheduler module (renamed types, improved error variants)

- Update workspace: add `obipipeline` member to Cargo.toml and lockfile  
- Document pipeline in docmd/implementation with full architecture, error handling & example
- Refactor sandbox_pipeline.rs to use new DSL instead of manual channel wiring

src/Cargo.toml

@@ -1,3 +1,3 @@
 [workspace]
 resolver = "3"
-members = ["obikseq", "obiread", "obiskbuilder", "obifastwrite", "obikmer","obikrope"]
+members = ["obikseq", "obiread", "obiskbuilder", "obifastwrite", "obikmer","obikrope","obipipeline"]