Modernize Swift assertion behavior and optional helper APIs

[jjamminjim]

Summary

This PR modernizes the Swift-side debugging and assertion utilities while preserving the package vocabulary and the existing Objective-C bridge surface.

What Changed

• made inform and informIf active in all build configurations and added a swappable DBCLogger protocol with DBCDebugPrintLogger as the default implementation
• updated check, ensure, and related failure helpers so release builds log through inform, while debug builds retain the existing assertion behavior and fallback logging when intensity suppresses a debug assertion
• simplified the default Swift Assertions closures to delegate directly to Swift assertion primitives instead of raising NSException first
• introduced DBCOptionalError for the throwing Optional helpers, improved Objective-C NSError bridging metadata, and tightened error/log formatting
• centralized mutable Swift configuration behind locked storage to remove obvious data races without changing the public API shape
• refreshed README/API docs, contributor guidance, and regression coverage across Swift, Objective-C, and bridged test targets

Behavior Notes

• default Swift assertion failures are now reported as Swift runtime traps/preconditions unless consumers override Assertions.*
• performIfDBCIntensity, inform, and informIf now honor intensity in all builds rather than compiling out in release
• check and ensure still surface failures through inform when debug assertions are suppressed by intensity

Testing

• swift test
• swift test -c release
• targeted regression runs during review, including:
  • swift test --filter SwiftDBCTests
  • swift test --filter SwiftDBCBridgedTests
  • swift test --filter RequiredOptionalTests
  • swift test -c release --filter SwiftDBCTests
  • swift test -c release --filter RequiredOptionalTests

Notes

• RequiredOptionalTests.swift still emits existing XCTest warnings about #fileID vs #filePath; that warning predates the PR finalization and was left out of scope for this change set.

[jjamminjim]

@pjvea : Hope this finds you well. Let me know if you have any questions.

[pjvea]

Great work! :)