fix: a watched callsign is never parked; refuse uploads to unconfigured services

ZD8GB — watch-listed, six streams a period, two of them RR73 — was
refused as "parked" for the rest of the session. Parking answers "it
will not answer, stop wasting the evening on it", which is a fair verdict
about a station the LOG picked out and the wrong one about a station the
OPERATOR named: a DXpedition running a pileup takes more than two series
of calls to get through to, which is exactly why it is on the list. The
rest between series still applies, so it cannot monopolise the
transmitter — it simply never becomes ineligible.

Send to (right-click) now refuses a service with no credentials and says
which are missing. The upload runs on its own goroutine and reports into
the QSL Manager's console, which is not open when the command came from
the QSO list, so an upload to an unconfigured service looked exactly like
one that worked. The toast is also raised only once the backend has
accepted the request, and Cloudlog / Wavelog and HamQTH name themselves
in it.

internal/autocall/autocall_test.go

@@ -922,3 +922,27 @@ func TestTheFirstCallStartsWithNoMisses(t *testing.T) {
 		t.Fatalf("misses=%d — the station's own silent period was not counted", e.misses)
 	}
 }
+
+// Parking answers "it will not answer, stop wasting the evening on it" — which
+// is a verdict about a station the LOG picked out, not about one the OPERATOR
+// did. From the air: a watched ZD8GB, six streams a period, refused for the
+// rest of the session after two series of unanswered calls.
+func TestAWatchedCallsignIsNeverParked(t *testing.T) {
+	spent := func(c Candidate) *Engine {
+		e := New(Settings{Enabled: true, MaxRounds: 2, Rest: 0})
+		for i := 0; i < 2; i++ {
+			e.giveUp(strings.ToUpper(c.Call), c) // a series ended by a brake
+		}
+		return e
+	}
+
+	plain := cq("PLAIN", NeedDXCC, 0)
+	if a := spent(plain).OnPeriod(period(0, plain)); a.Kind == DoReply {
+		t.Errorf("%+v — a station whose series are spent was called again", a)
+	}
+
+	dx := cq("ZD8GB", NeedDXCC, 0, watched)
+	if a := spent(dx).OnPeriod(period(0, dx)); a.Kind != DoReply {
+		t.Errorf("%+v — a watched DXpedition was parked for the session", a)
+	}
+}