[elliette]

This PR adds Material 3 Expressive typography to material_ui.

New APIs:

• Typography.material2025: a new factory constructor for M3 Expressive typography. NOTE: .material2025 replaces .material2021 as the default when useMaterial3 is true. Baseline styles are the same as material2021, but material2025 adds 15 new emphasized styles as well.
• Geometry text themes: Typography.englishLike2025, Typography.dense2025, and Typography.tall2025
• Emphasized text styles on TextTheme: an emphasized variant of each of the 15 baseline styles (e.g. TextTheme.titleMediumEmphasized). Only set by default when typography is created with material2025.
• Color-free typeface text themes: Typography.mountainView, Typography.redmond, Typography.helsinki, Typography.cupertino, and Typography.redwoodCity.

Demo (in material_ui/example):

Fixes flutter/flutter#184933

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Footnotes

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[gemini-code-assist]

Code Review

This pull request introduces Material 3 Expressive (2025) typography defaults, adding Typography.material2025 and corresponding emphasized text styles to TextTheme. It updates ThemeData to use these new defaults when useMaterial3 is true and adds platform-specific typeface text themes. Feedback suggests refactoring the switch expression in Typography.material2025 to handle a nullable platform parameter directly, avoiding the null-assertion operator.