immut/matrix Design

Responsibilities

• Provide a value-oriented Matrix[T] whose transformation methods return new matrices.
• Keep matrix storage row-major through the immutable vector-backed representation.
• Keep checked matrix operations explicit: shape, exponent, and domain failures belong in Result[..., LinearAlgebraError].

Invariants

• Constructors reject negative dimensions and non-rectangular input.
• Indexed access and row/column iterators enforce the same bounds rules as the mutable matrix API.
• Matrix algebra should stay aligned with mutable where both packages expose the same operation, while preserving value semantics.