Rename the settings whose names do not say what they control (closes #234)

Applies the setting renames of the naming audit under the SWW_WAF_ and
SWW_RPROXY_ prefixes, with sneak's names for the IP reputation cache
time and the two time limits, which now take milliseconds. The rproxy
log field default_disposition becomes waf_backend_no_answer, and
config.Config and config.FromEnvironment become config.WAF and
config.WAFFromEnvironment. Go fields, test names and prose follow. No
aliases; nothing reads the old names.

Model: opus-5-5

internal/ratelimit/ratelimit_test.go

@@ -361,7 +361,7 @@ func TestRefusalsOverTheThresholdInAMinuteBreakTheErrorBurst(t *testing.T) {
 	for range limit {
 		if _, over := limiter.CountRefusal(client, start, limit); over {
 			t.Fatalf(
-				"a refusal within the threshold of %d broke the error burst",
+				"a refusal within the threshold of %d broke the refusal limit",
 				limit,
 			)
 		}