chore: release 0.2.1 with crates.io metadata

Share version, edition, license, authors, repository and readme through
[workspace.package]; add per-crate documentation, keywords and
categories. Fixes `cargo publish` warning about missing documentation,
homepage or repository.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.toml

@@ -1,3 +1,11 @@
 [workspace]
 members = ["tines-core", "tines-sim"]
 resolver = "2"
+
+[workspace.package]
+version = "0.2.1"
+edition = "2021"
+license = "Apache-2.0"
+authors = ["K. Isom"]
+repository = "https://github.com/kisom/tines"
+readme = "README.md"