build: upgrade SwiftFormat to 0.58.7

[robmaceachern]

Summary

Upgrade SwiftFormat from 0.54.2 to 0.58.7 to support Swift 6.2 raw identifiers, including human-readable Swift Testing function names.

Changes

• Pin 0.58.7 in the existing mise configuration; local tooling and CI use the same version.
• Explicitly disable the six default rules added since the previous formatter version, preserving the repository's enabled rule set. Adopting those rules remains a separate style decision.
• Apply five small mechanical source cleanups required by existing rules: remove five blank lines and express one generic protocol requirement using the equivalent some WorkflowUIEvent parameter spelling.

Validation

• mise exec -- swiftformat --version reports 0.58.7.
• mise exec -- swiftformat --lint . --cache ignore: 0/283 files require formatting; 22 files skipped by formatter/configuration rules.
• The old 0.54.2 formatter passed the unchanged main-source baseline. A standalone Swift Testing fixture with a backticked, space-containing function name fails its parser and passes lint under 0.58.7 with this repository's configuration.
• git diff --check passes. Application, UI, and snapshot suites were not rerun locally; CI remains the build/test validation gate.

Checklist

• Unit Tests
• UI Tests
• Snapshot Tests (iOS only)
• I have made corresponding changes to the documentation (configuration comments explain preserved rule defaults)

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This response was drafted with AI assistance.