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.lock

@@ -548,7 +548,7 @@ dependencies = [
 
 [[package]]
 name = "tines-core"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "blake2",
  "heapless",
@@ -558,7 +558,7 @@ dependencies = [
 
 [[package]]
 name = "tines-sim"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "proptest",
  "rand 0.8.8",