feat: El port — vessels populated alongside Rust

Adds src/main.el + manifest.el for each vessel in this workspace,
ported from the Rust sources during the El consolidation pass on
2026-04-30. Each vessel now has both Rust (legacy) and El (target)
sources side-by-side; Rust will be removed once the El paths are
verified at runtime, vessel by vessel.

Per-vessel work was split across multiple parallel agents reading the
Rust to understand intent, then designing idiomatic El. Not 1:1
transliteration. Each ported vessel includes:
  - manifest.el per spec/language.md \u00a715.1
  - src/main.el with the vessel's public surface
  - Compile verified via dist/platform/elc + cc against the el_runtime

Known gaps surfaced during the port (held for follow-up): HMAC-SHA256
and base64 crypto, HTTP status code in handler returns, request
headers in handler signatures, subprocess primitives, streaming
responses, struct/enum types, browser/JS codegen target. Codegen bug
list of 9 items tracked separately. The El sources here are runtime-
ready under the canonical C runtime; the gaps are language/runtime
extensions still in flight.

ide/vessels/el-ide-server/manifest.el

@@ -0,0 +1,18 @@
+// manifest.el — el-ide-server vessel
+
+vessel "el-ide-server" {
+    version "0.1.0"
+    description "Engram IDE backend: HTTP server, file ops, build/run, LSP bridge, plugin host, settings."
+    authors ["Will Anderson <will@neurontechnologies.ai>"]
+    edition "2026"
+}
+
+dependencies {
+    el-lsp "0.1"
+    el-plugin-host "0.1"
+}
+
+build {
+    entry "src/main.el"
+    output "dist/"
+}