rename crates/ → vessels/ — El's word for buildable units

Per the consolidation onto El: 'crates' is the Rust word, 'vessel' is
El's (per spec/language.md §15). The directory rename is the structural
marker that this slot holds an El buildable unit, even if its current
contents are still Rust pending port.

Mechanical: git mv crates vessels, sed workspace members and any path
dependencies, update CI workflow paths, update README references.
Cross-repo path dependencies (`../foo/crates/bar`) updated workspace-
wide so cargo metadata still resolves where the Rust still builds.

vessels/el-ide-server/Cargo.toml

@@ -0,0 +1,34 @@
+[package]
+name = "el-ide-server"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "el-ide"
+path = "src/main.rs"
+
+[dependencies]
+el-lsp         = { workspace = true }
+el-plugin-host = { workspace = true }
+
+serde       = { workspace = true }
+serde_json  = { workspace = true }
+thiserror   = { workspace = true }
+tokio       = { workspace = true }
+axum        = { workspace = true }
+tower-http  = { workspace = true }
+rust-embed  = { workspace = true }
+tracing             = { workspace = true }
+tracing-subscriber  = { workspace = true }
+reqwest             = { workspace = true }
+async-stream        = { workspace = true }
+tokio-stream        = { workspace = true }
+which               = { workspace = true }
+urlencoding         = "2"
+mime_guess          = { workspace = true }
+futures-util        = { workspace = true }
+
+[dev-dependencies]
+tokio       = { workspace = true, features = ["macros", "rt"] }
+tower       = "0.5"