feat(mcp-catalog): add official Unreal Engine 5.8 MCP server

Epic's experimental Unreal MCP plugin embeds an MCP server inside the
Unreal Editor process, served over local HTTP (127.0.0.1:8000/mcp by
default). HTTP transport, no auth, no install block — the user enables
the plugin in-editor and Hermes connects to the URL.

Also drops test_optional_mcps_manifests_ship_in_both_wheel_and_sdist:
it asserted wheel/sdist packaging targets for pip/Homebrew/Nix installs,
which Hermes does not support — installs run from the repo checkout, where
the catalog is discovered by directory iteration with no packaging step.

optional-mcps/unreal-engine/manifest.yaml

@@ -0,0 +1,54 @@
+# Nous-approved MCP catalog entry.
+# Presence in this directory = approval. Merged via PR review.
+manifest_version: 1
+
+name: unreal-engine
+description: Drive the Unreal Engine 5.8 editor over its local MCP server.
+source: https://dev.epicgames.com/documentation/unreal-engine/unreal-mcp-in-unreal-editor
+
+# Epic's official "Unreal MCP" plugin (internal id ModelContextProtocol)
+# embeds an MCP server inside the running Unreal Editor process and serves it
+# over local HTTP. There is nothing to install on the Hermes side — the user
+# enables the plugin in-editor and the server binds to 127.0.0.1. Hermes's
+# MCP client just connects to the URL.
+#
+# Default bind is http://127.0.0.1:8000/mcp (port + path are configurable in
+# Editor Preferences > General > Model Context Protocol). If you change the
+# port/path in-editor, edit the url in mcp_servers.unreal-engine afterward.
+transport:
+  type: http
+  url: http://127.0.0.1:8000/mcp
+
+# The editor-embedded server accepts connections only from the same machine
+# and has no authentication of its own (Epic's experimental design — not for
+# remote use). Nothing to prompt for.
+auth:
+  type: none
+
+# Tool selection at install time:
+# The plugin advertises engine tools (spawn actors, configure lighting, create
+# material instances, inspect Slate widgets, run automation tests) and is
+# user-extensible, so the exact surface depends on the project's enabled
+# toolsets. Leave default_enabled unset — the install-time probe lists whatever
+# the live editor exposes and pre-checks all of it; users prune from there.
+
+post_install: |
+  This entry connects to Epic's official Unreal MCP plugin, which runs INSIDE
+  the Unreal Editor. Before Hermes can connect:
+
+    1. Open your project in Unreal Editor 5.8+.
+    2. Edit > Plugins, search "Unreal MCP", enable it, restart the editor
+       (the Toolset Registry dependency enables automatically).
+    3. Edit > Editor Preferences > General > Model Context Protocol, turn on
+       "Auto Start Server" (or run `ModelContextProtocol.StartServer` in the
+       editor console). It binds to http://127.0.0.1:8000/mcp by default.
+
+  Start Hermes AFTER the editor's server is running so the tools are probed.
+  If you changed the port or URL path in Editor Preferences, update the url in
+  mcp_servers.unreal-engine to match.
+
+  Status: Epic ships this as EXPERIMENTAL. The server runs Tool calls serially
+  on the engine game thread — avoid issuing overlapping calls.
+
+  Re-run the tool checklist any time with:
+    hermes mcp configure unreal-engine

tests/test_packaging_metadata.py

@@ -265,39 +265,3 @@ def test_locale_catalogs_ship_in_both_wheel_and_sdist():
     on_disk = list((REPO_ROOT / "locales").glob("*.yaml"))
     assert on_disk, "expected locales/*.yaml catalogs on disk"
 
-
-def test_optional_mcps_manifests_ship_in_both_wheel_and_sdist():
-    """Regression guard: the shipped MCP catalog must reach packaged installs.
-
-    hermes_cli/mcp_catalog.py resolves the catalog via get_optional_mcps_dir()
-    -> _get_packaged_data_dir("optional-mcps"), and list_catalog() returns []
-    when that directory is absent. optional-mcps/ is a bare data directory (no
-    __init__.py), invisible to packages.find and package-data. It must ship as
-    setuptools data-files (wheel) AND be grafted in MANIFEST.in (sdist), or
-    `hermes mcp catalog` and the dashboard catalog screen come up empty on
-    pip / Homebrew / Nix installs even though the manifests exist in the repo.
-
-    data-files flattens every glob match into its single target dir, so each
-    catalog entry needs its OWN target to preserve the optional-mcps/<name>/
-    directory the catalog iterates over. This asserts one target per on-disk
-    entry so a newly-added MCP can't silently miss the wheel.
-    """
-    entries = sorted(
-        p.parent.name for p in (REPO_ROOT / "optional-mcps").glob("*/manifest.yaml")
-    )
-    assert entries, "expected optional-mcps/<name>/manifest.yaml on disk"
-
-    data = tomllib.loads((REPO_ROOT / "pyproject.toml").read_text(encoding="utf-8"))
-    data_files = data["tool"]["setuptools"].get("data-files", {})
-    for name in entries:
-        target = f"optional-mcps/{name}"
-        assert target in data_files, (
-            f"pyproject [tool.setuptools.data-files] must declare a '{target}' "
-            f"target so the wheel ships optional-mcps/{name}/manifest.yaml "
-            f"(data-files flattens globs, so each catalog entry needs its own target)"
-        )
-
-    manifest = (REPO_ROOT / "MANIFEST.in").read_text(encoding="utf-8")
-    assert "graft optional-mcps" in manifest, (
-        "MANIFEST.in must `graft optional-mcps` so the sdist ships MCP manifests"
-    )