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

@@ -351,7 +351,9 @@ func TestResetSetsTheBytesBackToZero(t *testing.T) {
 	wantBytesCount(t, limiter, client, start, 1000, "")
 }
 
-func TestRefusalsOverTheThresholdInAMinuteBreakTheErrorBurst(t *testing.T) {
+func TestRefusalsOverTheLimitInAMinuteBreakTheRefusalLimit(
+	t *testing.T,
+) {
 	t.Parallel()
 
 	limiter := ratelimit.New(ratelimit.Limits{}, tableSize)
@@ -361,7 +363,7 @@ 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 limit of %d broke the refusal limit",
 				limit,
 			)
 		}
@@ -374,7 +376,7 @@ func TestRefusalsOverTheThresholdInAMinuteBreakTheErrorBurst(t *testing.T) {
 	}
 	if !over || hit != want {
 		t.Errorf(
-			"one over the threshold broke it: %t, with %+v; want %+v",
+			"one over the limit broke it: %t, with %+v; want %+v",
 			over,
 			hit,
 			want,
@@ -382,7 +384,7 @@ func TestRefusalsOverTheThresholdInAMinuteBreakTheErrorBurst(t *testing.T) {
 	}
 
 	// Half a minute into the next, half of those four still count, 2, and
-	// this one: 3, within the threshold.
+	// this one: 3, within the limit.
 	hit, over = limiter.CountRefusal(
 		client,
 		start.Add(time.Minute+time.Minute/2),