Version 0.6.0 (#444)

Minor bump: the SolidCraft rename (#389) and the design container format (#327) both change
the files people work with; builds 0.5 and older can't open designs saved by 0.6. Release
notes cover the new format, what's new and the upgrade from SolveCraft.


Claude-Session: https://claude.ai/code/session_01HWLPLy7ug7URSK5WybjRNa

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.toml

@@ -5,7 +5,7 @@ members = ["crates/*", "apps/*", "xtask"]
 exclude = ["vendor"]
 
 [workspace.package]
-version = "0.5.0"
+version = "0.6.0"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 rust-version = "1.95"