feat: add C implementation for blas/ext/base/ndarray/sfill

[AryanSharma48]

Part of #14404.

Description

What is the purpose of this pull request?

This pull request:

• adds the ndarray interface for @stdlib/blas/ext/base/ndarray/sfill.
• wraps and delegates directly to @stdlib/blas/ext/base/sfill's .ndarray method by extracting inputs from an arrays array-like object.
• adds unit tests, benchmarks, examples, and TypeScript definitions following the dsum and daxpb canonical references.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• Part of [RFC]: add ndarray interface variants for missing modules in @stdlib/blas/ext/base #14404

Questions

Any questions for reviewers of this pull request?

No.

Other

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No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

I used AI assistance to scaffold the TS tests, and documentation based on canonical reference packages (dsum, daxpb), followed by manual review, local tape tests, and lint verification.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/ndarray/sfill	$\\color{green}142/142$ $\\color{green}+0.00\\%$	$\\color{green}5/5$ $\\color{green}+0.00\\%$	$\\color{green}1/1$ $\\color{green}+0.00\\%$	$\\color{green}142/142$ $\\color{green}+0.00\\%$

The above coverage report was generated for the changes in this PR.

[AryanSharma48]

Hey @0PrashantYadav0 ! I have a question regarding the architectural design for @stdlib/blas/ext/base/ndarray/sfill.

Currently, I've implemented it as a pure JavaScript wrapper that delegates directly to the underlying strided C implementation via @stdlib/blas/ext/base/sfill (similar to how sfill-nan and dfill-nan are structured).

However, I noticed that some packages like @stdlib/blas/ext/base/ndarray/dsum have their own dedicated C addon (src/addon.c, binding.gyp, etc.) and serialize the metadata directly to C.

Should sfill remain a pure JS delegator to @stdlib/blas/ext/base/sfill, or do you prefer that I implement a dedicated C addon and compile configuration for it similar to dsum?