🐍 refactor: Normalize Non-Standard Browser MIME Type Aliases in inferMimeType

[danny-avila]

Summary

Fixes Python file uploads being rejected on macOS, where Chrome and Firefox report .py files as text/x-python-script instead of the canonical text/x-python, causing client-side MIME validation to fail.

• Introduces a mimeTypeAliases constant (Readonly<Record<string, string>>) in file-config.ts that maps known non-standard browser-reported MIME types to their canonical equivalents.
• Extends inferMimeType to apply alias normalization before returning when the browser provides a non-empty type, so the corrected type propagates through both client-side validation and the upload form payload.
• Restores and improves the inferMimeType JSDoc with @param and @returns annotations, including documenting the empty-string return case.
• Adds two checkType integration tests that assert the before/after validation boundary directly: the raw text/x-python-script is rejected without normalization, and the normalized text/x-python is accepted.
• Removes three redundant inferMimeType unit tests from DragDropModal.spec.tsx that duplicated coverage already present in file-config.spec.ts.
• Corrects import sort order in file-config.spec.ts to longest-to-shortest per project conventions.

Change Type

• Bug fix (non-breaking change which fixes an issue)

Testing

Ran the full packages/data-provider test suite. The two new integration tests explicitly cover the broken state (raw text/x-python-script fails checkType) and the fixed state (normalized text/x-python passes checkType).

To reproduce the original bug manually: on macOS, open Chrome or Firefox, navigate to the chat input, and attempt to attach a .py file. Without this fix, the upload is rejected with an unsupported file type error. With this fix, the file is accepted and uploaded as text/x-python.

Test Configuration:

• macOS (Chrome or Firefox) to reproduce the original browser MIME type behavior
• cd packages/data-provider && npx jest inferMimeType to run the targeted unit and integration tests

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes

[Copilot]

Pull request overview

This PR fixes Python MIME type validation by normalizing a non-standard browser-reported MIME type (text/x-python-script) to the canonical text/x-python, ensuring it passes existing MIME regex checks and downstream validations.

Changes:

• Added a mimeTypeAliases map and applied it inside inferMimeType when a browser-provided MIME type is present.
• Added unit tests in packages/data-provider for normalization and extension-based inference.
• Added client-side test coverage to ensure UI-related MIME inference behavior is consistent.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/data-provider/src/file-config.ts	Introduces MIME alias normalization and applies it in inferMimeType.
packages/data-provider/src/file-config.spec.ts	Adds tests validating alias normalization and inference behavior.
client/src/components/Chat/Input/Files/tests/DragDropModal.spec.tsx	Adds client test coverage for the new alias normalization behavior.

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