AS number and country looked up for every client (closes #95)

GeoJS's geo.json is asked about every new visitor unless
SWWAF_LOOKUP_SOURCE is off. A request waits for its client's first
answer only while a country list or SWWAF_ADD_LOOKUP_HEADERS needs it;
otherwise the answer reaches the client's history and ban notes when it
comes. The AS number and name go beside the country in the request log,
history, ban notes, alerts and lookups.json, with metrics by AS number;
64512 counts as unknown.

Judgement call: AS numbers are written AS64496, as SPEC's settings write them.
Judgement call: SWWAF_LOOKUP_TIMEOUT is added, default 1s, and cannot be off.
Judgement call: a client's own X-Client-* headers are removed only while SWWAF_ADD_LOOKUP_HEADERS is set.

Model: opus-5-5

internal/lookup/snapshot_test.go

@@ -26,8 +26,11 @@ func TestSnapshotHoldsEachAnswerAndWhenItWasLastUsed(t *testing.T) {
 		wantCountry(t, g, placed, germany)
 
 		want := []lookup.Answer{
-			{Client: notPlaced, Country: "", Answered: asked, Used: asked},
-			{Client: placed, Country: germany, Answered: asked, Used: asked.Add(time.Hour)},
+			{Client: notPlaced, Answered: asked, Used: asked},
+			{
+				Client: placed, ASN: asn, ASName: asName, Country: germany,
+				Answered: asked, Used: asked.Add(time.Hour),
+			},
 		}
 		if got := g.Snapshot(); !slices.Equal(got, want) {
 			t.Errorf("snapshot\n%+v\nwant\n%+v", got, want)