Name log fields, metrics and the Core Rule Set package for what they are (closes #192)

The first half of the naming audit: names now say what they are. `internal/waf` is `internal/coreruleset`. Log fields, the action `blocked_by_core_rule_set`, the metric and the alert event say Core Rule Set. Timings end `_ms`. Percentages say of what, as `rate_limit_percent` and `bytes_limit_percent`. Setting names follow in #234.

Judgement call: `blocked_by_core_rule_set`, not the audit's `core_rule_set_blocked`, to match `blocked_by_block_rule`.
Trips a reader: an existing state file holding `waf_blocked` or the anomaly scope `watch` stops the start and must be removed. `SWW_ALERT_EVENTS` listing `waf_block` must list `core_rule_set_match`.

Model: opus-5-5

internal/rproxy/rproxy_test.go

@@ -727,7 +727,7 @@ func TestDenyGivesTheVisitorDiscriminatorsAnswer(t *testing.T) {
 	report := standIn.report(t)
 	if report.Status != http.StatusForbidden ||
 		report.ResponseBytes != int64(len(deniedBody)) ||
-		report.DurationUpstreamTotal != 0 {
+		report.DurationUpstreamTotalMS != 0 {
 		t.Errorf("report %+v, of a request denied", report)
 	}
 
@@ -871,9 +871,9 @@ func TestALineForARequestClosedWithoutAnAnswerHasNoNegativeTime(t *testing.T) {
 
 		line := out.requestLine(t)
 
-		duration, ok := line["duration_response"].(float64)
+		duration, ok := line["duration_response_ms"].(float64)
 		if !ok || duration < 0 {
-			t.Errorf("line %v, want a duration_response that is not negative", line)
+			t.Errorf("line %v, want a duration_response_ms that is not negative", line)
 		}
 	}
 }
@@ -1428,8 +1428,8 @@ func TestReportGivesWhatHappened(t *testing.T) {
 	if report.RequestID == "" || report.Status != http.StatusOK ||
 		report.RequestBytes != int64(len(body)) ||
 		report.ResponseBytes != int64(len(greeting)) ||
-		report.DurationTotal <= 0 || report.DurationUpstreamTotal <= 0 ||
-		report.DurationUpstreamTotal > report.DurationTotal {
+		report.DurationTotalMS <= 0 || report.DurationUpstreamTotalMS <= 0 ||
+		report.DurationUpstreamTotalMS > report.DurationTotalMS {
 		t.Errorf("report %+v, of %d bytes up and %d back", report, len(body), len(greeting))
 	}
 
@@ -1748,7 +1748,7 @@ func TestLogLineGivesTheRequestAsSent(t *testing.T) {
 		t.Errorf("default_disposition is %v, want it left out", line["default_disposition"])
 	}
 
-	for _, name := range []string{"duration_request", "duration_response"} {
+	for _, name := range []string{"duration_request_ms", "duration_response_ms"} {
 		duration, ok := line[name].(float64)
 		if !ok || duration <= 0 {
 			t.Errorf("%s is %v, want a time", name, line[name])