Remove Cargo.toml files from el-ui — vessels use manifest.el

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).

ui/vessels/el-config/Cargo.toml

@@ -1,18 +0,0 @@
-[package]
-name = "el-config"
-version = "0.1.0"
-edition = "2021"
-description = "el-ui configuration system — layered, typed, environment-aware"
-license = "MIT"
-
-[lib]
-name = "el_config"
-path = "src/lib.rs"
-
-[dependencies]
-thiserror = "1"
-serde = { version = "1", features = ["derive"] }
-serde_json = "1"
-toml = "0.8"
-
-[dev-dependencies]