docs(search): don't threshold JSON score as Tavily

S1: skill recipe now says result score is merged rank. Also send
non-zero --min-score to the server (N1), sort include_domains (N2),
and note that search_queries counts each sub-query (N3).

internal/search/p31_test.go

@@ -150,6 +150,18 @@ func TestNormalizeDomainOR(t *testing.T) {
 	if msg != "" || hint != "" || len(out.IncludeDomains) != 1 || out.IncludeDomains[0] != "oracle.com" {
 		t.Fatalf("%q %q %+v", msg, hint, out)
 	}
+	_, out, msg, _ = NormalizeSearch("q", nil, Filter{IncludeDomains: []string{"z.com", "a.com", "m.com"}})
+	if msg != "" || strings.Join(out.IncludeDomains, ",") != "a.com,m.com,z.com" {
+		t.Fatalf("sorted domains %+v", out.IncludeDomains)
+	}
+	_, four, _, _ := NormalizeSearch("q", nil, Filter{IncludeDomains: []string{"d.com", "c.com", "b.com", "a.com"}})
+	q, notes := searxQueryAndNotes("q", four)
+	if !strings.HasPrefix(q, "site:a.com OR site:b.com OR site:c.com ") {
+		t.Fatalf("site subset %q", q)
+	}
+	if !strings.Contains(strings.Join(notes, " "), "extra include_domains dropped") {
+		t.Fatalf("notes %v", notes)
+	}
 }
 
 func TestMultiQueryRRF(t *testing.T) {