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/discriminator/requestlog_test.go

@@ -156,9 +156,9 @@ func wantBareLine(t *testing.T, line logLine) {
 
 // withTimings returns want with the timings of line.
 func withTimings(line logLine, want requestlog.Line) requestlog.Line {
-	want.DurationTotal = line.DurationTotal
-	want.DurationChecks = line.DurationChecks
-	want.DurationUpstreamTotal = line.DurationUpstreamTotal
+	want.DurationTotalMS = line.DurationTotalMS
+	want.DurationChecksMS = line.DurationChecksMS
+	want.DurationUpstreamTotalMS = line.DurationUpstreamTotalMS
 
 	return want
 }
@@ -226,10 +226,10 @@ func TestTimingsAreInOrder(t *testing.T) {
 
 	// A request passed to the app has every timing; one refused, none of
 	// the app's; the health check, which runs no check, only the total.
-	wantTimings(t, forwarded, "duration_total", "duration_checks",
-		"duration_upstream_total")
-	wantTimings(t, refused, "duration_total", "duration_checks")
-	wantTimings(t, health, "duration_total")
+	wantTimings(t, forwarded, "duration_total_ms", "duration_checks_ms",
+		"duration_upstream_total_ms")
+	wantTimings(t, refused, "duration_total_ms", "duration_checks_ms")
+	wantTimings(t, health, "duration_total_ms")
 
 	if t.Failed() {
 		return
@@ -237,9 +237,9 @@ func TestTimingsAreInOrder(t *testing.T) {
 
 	// In whole microseconds, as they are logged, so that the sum below is
 	// exact.
-	total := microseconds(forwarded.DurationTotal)
-	checks := microseconds(*forwarded.DurationChecks)
-	upstream := microseconds(*forwarded.DurationUpstreamTotal)
+	total := microseconds(forwarded.DurationTotalMS)
+	checks := microseconds(*forwarded.DurationChecksMS)
+	upstream := microseconds(*forwarded.DurationUpstreamTotalMS)
 
 	// The checks end before the request is handed to the app.
 	if checks+upstream > total {
@@ -247,9 +247,9 @@ func TestTimingsAreInOrder(t *testing.T) {
 			total, checks, upstream)
 	}
 
-	if *refused.DurationChecks > refused.DurationTotal {
+	if *refused.DurationChecksMS > refused.DurationTotalMS {
 		t.Errorf("refused request's checks took %v of %v milliseconds",
-			*refused.DurationChecks, refused.DurationTotal)
+			*refused.DurationChecksMS, refused.DurationTotalMS)
 	}
 }