feat: el-ide — native IDE for engram-lang, LSP, type graph, plugin ecosystem

Axum HTTP server (port 7771) serving a single-page IDE with CodeMirror 6
syntax highlighting for engram-lang, a force-directed type graph visualizer,
LSP (completions, hover, diagnostics), SSE-streamed build/run output, a
plugin host with five first-party plugins, and a reasoning panel that proxies
to engram-server. 28 tests across three crates, zero warnings.

crates/el-lsp/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "el-lsp"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+el-lexer    = { workspace = true }
+el-parser   = { workspace = true }
+el-types    = { workspace = true }
+serde       = { workspace = true }
+serde_json  = { workspace = true }
+thiserror   = { workspace = true }
+
+[dev-dependencies]