fix(ts/formatter): format comment after => in arrow functions

[mdm317]

This PR was created with Codex assistance.

fixes: #8959

Summary

Made formatting consistent for comments right after => in TypeScript arrow return types.

Test Plan

Added test code.

[changeset-bot]

🦋 Changeset detected

Latest commit: fa20000

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

Not sure what this means? Click here to learn what changesets are.

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[codspeed-hq]

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 156 skipped benchmarks¹

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_{Comparing mdm317:fix/ts-arrow-after-comment (fa20000) with main (61f53ee)²}

Footnotes

1. 156 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (bc709f6) during the generation of this report, so 61f53ee was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between a816627 and fa20000.

📒 Files selected for processing (1)

• .changeset/cuddly-dogs-hide.md

🚧 Files skipped from review as they are similar to previous changes (1)

• .changeset/cuddly-dogs-hide.md

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Walkthrough

Adds handling for TypeScript function types when placing comments that appear after the fat arrow (=>) so such comments become leading comments on the following node (or default if none). Adds tests covering inline and separate-line comments after the arrow in TypeScript function types. Adds a changelog entry for a patch release referencing issue #8959.

Suggested reviewers

• dyc3

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarises the main change: fixing TypeScript arrow function comment formatting after the fat arrow operator.
Description check	✅ Passed	The description is related to the changeset, referencing issue #8959 and explaining the fix for comment formatting consistency.
Linked Issues check	✅ Passed	The PR addresses all coding objectives from #8959: handling comments between => and return types consistently, with test cases added.
Out of Scope Changes check	✅ Passed	All changes are scoped to the issue requirements: changelog entry, formatter logic fix, and test file additions.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

📝 Coding Plan

• Generate coding plan for human review comments

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