Add /version slash command across CLI, gateway, TUI, and desktop.

Surfaces Hermes Agent version info on demand without leaving chat; works mid-run like /help and /update.

tests/gateway/test_version_command.py

@@ -0,0 +1,12 @@
+"""Tests for gateway /version command."""
+
+import asyncio
+
+from hermes_cli import __release_date__, __version__
+
+
+def test_gateway_version_command_returns_release_line():
+    from gateway.run import GatewayRunner
+
+    result = asyncio.run(GatewayRunner._handle_version_command(None, None))  # type: ignore[arg-type]
+    assert result == f"Hermes Agent v{__version__} ({__release_date__})"