Fix RichHandler surrogate logging on strict utf-8 streams

[lwhelton]

Type of changes

• [ X] Bug fix
• New feature
• Documentation / docstrings
• [] Tests
• Other

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• AI was used to generate this PR

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Checklist

• [X ] I've run the latest black with default args on new code.
• [X ] I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate (see note about typos above).
• [ X] I've added tests for new code.
• [ X] I accept that @willmcgugan may be pedantic in the code review.

Description

Fixes a UnicodeEncodeError in RichHandler when logging messages contain surrogate characters and the target stream uses strict UTF-8 encoding. The handler now escapes unencodable messages before constructing the final Rich text object, which preserves logging output instead of crashing. A regression test was added to cover strict UTF-8 stream behavior.
Important: Link to an issue or discussion regarding these changes.