chore: update ZCode to 3.11.2

[supermomonga]

Summary

Update ZCode version from 3.10.2 to 3.11.2 across all documentation, source code, and test fixtures. This includes:

• Updating host artifact descriptor ID and app version
• Refreshing CLI SHA-256 and host index SHA-256 hashes
• Updating documentation dates and version references
• Refreshing test fixtures and test data to match new version
• Updating observed macOS build identifier

Changes

• Manifest: Updated CURRENT_ZCODE_ARTIFACT descriptor with new version and artifact hashes
• Type definitions: Updated HostArtifactId type to reflect new artifact version
• Documentation: Updated version references across architecture documentation and implementation status
• Test fixtures: Updated version numbers and expected hashes in compatibility tests

Testing

• Run bun run check to verify all 57 tests pass with new version
• Verify doctor --json reports zcode-host-3.11.2 and supported status
• Confirm CLI verification passes with new SHA-256 hash
• Test local runtime verification on macOS with ZCode 3.11.2 installed
• Verify manifest compatibility checks reject older/newer versions
• Confirm host artifact and protocol resolution uses correct descriptors