Env names in reload diff; monitor shows last VRAM check result; harden control channel against floods

- diffConfig reports the env var names (from new struct tags) instead of
  Go field names, so the reload-env reply names what the user can change
- the monitor's GPU line now shows the game detector's last finding
  (external holders or none) and how long ago the check ran
- control channel: 10s per-connection watchdog (abortive force-close),
  cap of 32 concurrent connections, reload-env rate-limited; command
  read was already capped at 4 KiB

internal/control/control_windows.go

@@ -86,7 +86,10 @@ func Serve(ctx context.Context, h Handler, log *slog.Logger) error {
 				windows.CloseHandle(pipe)
 				continue
 			}
-			go serveConn(&pipeConn{f: os.NewFile(uintptr(pipe), pipePath), h: pipe}, h)
+			conn := &pipeConn{f: os.NewFile(uintptr(pipe), pipePath), h: pipe}
+			if !serve(conn, h) {
+				conn.ForceClose()
+			}
 		}
 	}()
 	return nil
@@ -114,6 +117,14 @@ func (c *pipeConn) Close() error {
 	return c.f.Close()
 }
 
+// ForceClose aborts the connection without flushing: disconnecting
+// unblocks pending reads and writes at the cost of possibly discarding an
+// unread reply. Used by the connection watchdog; normal closes flush.
+func (c *pipeConn) ForceClose() error {
+	windows.DisconnectNamedPipe(c.h) //nolint:errcheck // best effort
+	return c.f.Close()
+}
+
 // Ask sends one command to the running service and returns its reply.
 func Ask(cmd string) (string, error) {
 	name, err := windows.UTF16PtrFromString(pipePath)