chore: add readme and homepage fields for crates.io publishing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: corvid-agent

Cargo.toml

@@ -4,6 +4,8 @@ version = "1.0.0"
 edition = "2024"
 description = "Bidirectional spec-to-code validation — language-agnostic, blazing fast"
 license = "MIT"
+readme = "README.md"
+homepage = "https://github.com/CorvidLabs/spec-sync"
 repository = "https://github.com/CorvidLabs/spec-sync"
 keywords = ["spec", "documentation", "validation", "coverage"]
 categories = ["development-tools", "command-line-utilities"]