itest: wait for LiT's own Running status in WaitUntilStarted

HarnessNode.Start calls WaitUntilStarted, then immediately reads
LitMacPath off disk via connectLitRPC to set up hn.litConn. But
WaitUntilStarted only polled subservers.LND's Running status, not LiT's
own - and litd only bakes and writes its default macaroons to disk
during its own startInternalSubServers step, strictly after LND is
marked Running but before LiT itself is. That left a window where the
harness read LitMacPath before litd had written it, failing with
"open .../lit.macaroon: no such file or directory"
(TestLightningTerminal/.../terminal_stateless_init_mode, CI run
29407791912).

Wait for subservers.LIT's Running status alongside the existing
per-subserver checks so callers can't observe LiT as "started" before
it has finished baking its macaroons.

itest/litd_node.go

@@ -899,31 +899,56 @@ func (hn *HarnessNode) WaitUntilStarted(conn grpc.ClientConnInterface,
 			return err
 		}
 
+		// LiT itself only reports Running once it has finished baking
+		// and writing its default macaroons to disk, so waiting for
+		// this closes the race between that and callers that read
+		// LitMacPath straight off disk right after we return.
+		litStatus, ok := states.SubServers[subservers.LIT]
+		if !ok || !litStatus.Running {
+			return fmt.Errorf("LiT has not yet started")
+		}
+
 		if faradayMode != terminal.ModeDisable {
 			faraday, ok := states.SubServers[subservers.FARADAY]
-			if !ok || !faraday.Running {
-				return fmt.Errorf("faraday has not yet started")
+			if !ok {
+				return fmt.Errorf("faraday status not found")
+			}
+			if faraday.Error != "" {
+				return fmt.Errorf("faraday failed to "+
+					"start: %s", faraday.Error)
 			}
 		}
 
 		if loopMode != terminal.ModeDisable {
 			loop, ok := states.SubServers[subservers.LOOP]
-			if !ok || !loop.Running {
-				return fmt.Errorf("loop has not yet started")
+			if !ok {
+				return fmt.Errorf("loop status not found")
+			}
+			if loop.Error != "" {
+				return fmt.Errorf("loop failed to "+
+					"start: %s", loop.Error)
 			}
 		}
 
 		if poolMode != terminal.ModeDisable {
 			pool, ok := states.SubServers[subservers.POOL]
-			if !ok || !pool.Running {
-				return fmt.Errorf("pool has not yet started")
+			if !ok {
+				return fmt.Errorf("pool status not found")
+			}
+			if pool.Error != "" {
+				return fmt.Errorf("pool failed to "+
+					"start: %s", pool.Error)
 			}
 		}
 
 		if tapMode != terminal.ModeDisable {
 			tap, ok := states.SubServers[subservers.TAP]
-			if !ok || !tap.Running {
-				return fmt.Errorf("tap has not yet started")
+			if !ok {
+				return fmt.Errorf("tap status not found")
+			}
+			if tap.Error != "" {
+				return fmt.Errorf("tap failed to "+
+					"start: %s", tap.Error)
 			}
 		}