By: ValentinHirschi <valentin.hirschi@gmail.com>
use Schoonschip notation for composite tensor contractions Restrict automatic dot construction to calls to rank-one-tagged vector heads. Generic and composite contractions retain indexed factors for Schoonschip collection; explicit dot() remains available. Allow supplied vectors to fill retained metric ports in both factorized and ordered contraction paths, including when metric elimination is disabled. Preserve factored scalar coefficients and add regression coverage for all metric/vector multiplication orders and explicit notation choices. Update the Python API documentation and regenerate its stubs. Validation: 358 tensor composition, contraction, parsing and printing tests pass. Idenso Clippy with all targets and warnings denied passes. Targeted rustfmt passes.