docs(itensorlike): improve documentation — layout, Complex64, API conventions

[shinaoka]

Summary

Several documentation gaps identified during feature testing of tensor4all-itensorlike.

Issues

Missing documentation

1. Column-major data layout not mentioned in crate README. Users need to know TensorDynLen::from_dense expects column-major data.
2. No Complex64 examples in README — all examples use f64 only.
3. Inner product conjugation convention (inner() computes <self|other> with conjugation on self) not prominently documented.
4. with_nsweeps() convenience method not mentioned in README alongside with_nhalfsweeps().

API discoverability

5. IndexLike trait must be imported for .dim() on DynIndex — consider re-exporting from tensor4all_itensorlike.
6. DynIndex::new_bond vs new_dyn asymmetry (one returns Result, the other doesn't) unexplained.
7. Relationship between CanonicalForm and TruncateAlg undocumented — truncate() implicitly sets canonical form based on algorithm.

Missing "Getting Started" content

8. Add a complete import list example including tensor4all_core::{DynIndex, TensorDynLen, TensorLike, AnyScalar}.
9. Show inner product workflow in README example.

Found by

Automated feature test (test-feature-20260327-itensorlike)