fix: recognize bunx.EXE/node.EXE argv0 on Windows (case-insensitive)

[deepshekhardas]

Fixes #36826

On Windows, executable-name detection compares argv0 case-sensitively: bunx.EXE (e.g. produced by PATH x PATHEXT resolution) is not recognized as bunx and bun misclassifies itself as plain bun, failing with error: Script not found. Same applies to node.exe vs NODE.EXE.

• Add strings::ends_with_case_insensitive_ascii (mirror of the existing starts_with_case_insensitive_ascii) in src/bun_core/string/immutable.rs + unit test
• Use it for is_bun_x/is_node on Windows in src/runtime/cli/mod.rs

[claude]

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Reviewing files that changed from the base of the PR and between 6324a58 and ded1aa7.

📒 Files selected for processing (2)

• src/bun_core/string/immutable.rs
• src/runtime/cli/mod.rs

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Walkthrough

The PR adds an ASCII case-insensitive suffix matcher and uses it to detect bunx and node executable names with varied casing on Windows. Tests cover matching, length mismatches, prefixes, and non-matching suffixes.

Changes

Windows executable detection

Layer / File(s)	Summary
ASCII suffix matcher src/bun_core/string/immutable.rs	Adds ends_with_case_insensitive_ascii and tests for case variants, suffix lengths, prefixes, and mismatches.
Windows CLI detection src/runtime/cli/mod.rs	Uses case-insensitive suffix matching for Windows bunx and node executable detection. Non-Windows detection remains unchanged.

Suggested reviewers: jarred-sumner, robobun

Merge Risk: ⚪ Minimal · up to ded1a

This PR makes a localized Windows executable-name matching fix for bunx and node, with no actionable merge-blocking risk remaining beyond normal checks and review.

🚥 Pre-merge checks | ✅ 3 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the bug and implementation, but it omits the required verification section and template headings.	Add the required headings and document how the code was verified, including relevant Windows tests.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the Windows case-insensitive executable-name fix.
Linked Issues check	✅ Passed	The changes address issue #36826 by recognizing case variations such as bunx.EXE and preserving correct bunx behavior on Windows.
Out of Scope Changes check	✅ Passed	The helper, unit test, and Windows detection changes are directly related to the executable-name casing problem.

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[robobun]

Thanks for the PR, @deepshekhardas. #36827 has been open for this same issue since Aug 3 and takes the same approach (an ASCII case-insensitive suffix helper used from is_bun_x / is_node), so I am closing this one in its favor rather than keeping two PRs open for #36826. What tipped it:

• cli: match bunx/node invocation names case-insensitively #36827 also switches the non-Windows branches, so the behavior is observable and tested on every platform. It adds invocation tests for both the bunx and node names (test/cli/install/bunx.test.ts, test/cli/run/as-node.test.ts), and the issue reporter verified its Windows build against the original repro.
• Its helper passes check_len = true to eql_case_insensitive_ascii. With check_len = false, as here, the comparator's debug assertions fire for an empty suffix. The current call sites never pass one, but the helper is public.
• Two notes on the unit test in this PR, in case they are useful: ends_with_case_insensitive_ascii(b"bunx.EXE", b"bunx") is false (the last four bytes are .EXE), so the third assertion would fail if run. The bun.exe / bunx mismatch case, on the other hand, was missing from cli: match bunx/node invocation names case-insensitively #36827, so I folded it in over there with a Co-authored-by credit to you.

If you see anything #36827 still misses, please comment over there.