Fix ndarray from_iterator for column-major input

[jolars]

Fixes #482

I've pulled this fix out of #480 so we can review and merge it on its own.

Current behaviour

The ndarray implementation of from_iterator first builds a row-major array, then reverses its axes and reshapes it for column-major input. That reshape can panic for rectangular matrices. For example, from_iterator(1..=6, 2, 3, 1) fails instead of producing [[1, 3, 5], [2, 4, 6]]. This also affects callers such as h_stack.

New expected behaviour

The constructor uses the requested order directly: row-major for axis = 0 and column-major for axis = 1. Column-major input now produces a column-major array with the expected values and dimensions.

Change logs

• Move the ndarray fix from feat: add lazy normalization for Lasso and Elastic Net #480 into this PR.
• Test both input orders, storage strides, empty dimensions, and h_stack. Both regression tests fail with the old implementation.
• Add a Fixed entry to the changelog.

Validation

I ran these checks locally with Rust 1.99.0:

cargo build --all-features
cargo test --all-features
cargo fmt --all -- --check
cargo clippy --all-features -- -Drust-2018-idioms -Drust-2024-compatibility -Dwarnings

Checklist

• My branch is up-to-date with main branch.
• Everything works and tested on latest stable Rust.
• Coverage and Linting have been applied.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.44%. Comparing base (9eaae9e) to head (e501c94).
⚠️ Report is 199 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #483       +/-   ##
===========================================
+ Coverage   43.97%   85.44%   +41.47%     
===========================================
  Files          85       96       +11     
  Lines        7281     9367     +2086     
===========================================
+ Hits         3202     8004     +4802     
+ Misses       4079     1363     -2716     

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[Mec-iS]

Thank you!