Remove extractFromFile

[mcmire]

Explanation

It seems extractFromFile was only used in tests but nowhere else. extractFromSourceFile is the true public method.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
API removal only affects consumers of the removed helper; extraction logic is untouched and tests preserve the same scenarios.

Overview
Removes the extractFromFile convenience API from platform-api-docs so callers use createExtractionProject plus extractFromSourceFile only—the path intended for real batch extraction.

Tests are updated to match: a shared extractFromWrittenFile helper writes fixtures, loads sibling .ts / .d.cts files into a project, and runs extractFromSourceFile. The suite is renamed from extractFromFile to extractFromSourceFile; extraction behavior is unchanged.

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