Rename the program to sww and its deciding daemon to discriminator

The program is now sww, built from cmd/sww, with two modes: sww rproxy and
sww discriminator. servewaf becomes discriminator everywhere it names that
daemon: the package (internal/discriminator), its types, functions, files, the
discriminator_line log field, and its docs and tests.

smallwebwaf is left only where sneak's directive allows it: the documents'
product name, the git.eeqj.de/sneak/smallwebwaf URLs, and the Go module path
sneak.berlin/go/smallwebwaf. Everywhere else a name containing it takes the sww
form: the package (internal/sww), metric names (sww_*), the X-Sww-* headers,
the /_sww/ admin endpoints, the SWW_COMMAND setting, the OS user, and the state
and rules directories.

No logic changes. make check passes.

Model: deepseek-v4-pro

internal/reputation/dnsbl_test.go

@@ -311,7 +311,7 @@ func TestMetricsCountEachZonesQueriesAndThoseThatFailed(t *testing.T) {
 			"queries_total" + `{instance="app",source="` + otherZone + `"}`:  "1",
 			"failures_total" + `{instance="app",source="` + otherZone + `"}`: "1",
 		} {
-			line := "\nsmallwebwaf_reputation_" + series + " " + want + "\n"
+			line := "\nsww_reputation_" + series + " " + want + "\n"
 			if !strings.Contains(scraped.Body.String(), line) {
 				t.Errorf("metrics\n%s\nwant%s", scraped.Body.String(), line)
 			}