Unix Domain Socket auto discovery (#833)

This PR adds end-to-end Unix domain socket (UDS) support, allowing zen CLI to discover and connect to UDS-only servers automatically.

- **`unix://` URI scheme in zen CLI**: The `-u` / `--hosturl` option now accepts `unix:///path/to/socket` to connect to a zenserver via a Unix domain socket instead of TCP.
- **Per-instance shared memory for extended server info**: Each zenserver instance now publishes a small shared memory section (keyed by SessionId) containing per-instance data that doesn't fit in the fixed-size ZenServerEntry -- starting with the UDS socket path. This is a 4KB pagefile-backed section on Windows (`Global\ZenInstance_{sessionid}`) and a POSIX shared memory object on Linux/Mac (`/UnrealEngineZen_{sessionid}`).
- **Client-side auto-discovery of UDS servers**: `zen info`, `zen status`, etc. now automatically discover and prefer UDS connections when a server publishes a socket path. Servers running with `--no-network` (UDS-only) are no longer invisible to the CLI.
- **`kNoNetwork` flag in ZenServerEntry**: Servers started with `--no-network` advertise this in their shared state entry. Clients skip TCP fallback for these servers, and display commands (`ps`, `status`, `top`) show `-` instead of a port number to indicate TCP is not available.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/zenserver/zenserver.h b/src/zenserver/zenserver.h
index 374184aa9..830f36e54 100644
--- a/src/zenserver/zenserver.h
+++ b/src/zenserver/zenserver.h
@@ -148,8 +148,9 @@ public:
 	ZenServerMain& operator=(const ZenServerMain&) = delete;
 
 protected:
-	ZenServerConfig& m_ServerOptions;
-	LockFile		 m_LockFile;
+	ZenServerConfig&	  m_ServerOptions;
+	LockFile			  m_LockFile;
+	ZenServerInstanceInfo m_InstanceInfo;
 
 	virtual void InitializeLogging();
 	virtual void DoRun(ZenServerState::ZenServerEntry* Entry) = 0;