All package management is through manifest.el / epm. Cargo.toml files
were incorrectly added to vessels and the root. Removed root workspace
Cargo.toml + Cargo.lock and all vessel-level Cargo.toml files.
el-graph and el-html were already correct (no Cargo.toml).
el-html is a standalone atomic emit layer; it has no runtime dependency on
el-style or el-layout (those vessels depend on el-html for SSR, not the other
way around).