Rename the program to sww and its deciding daemon to discriminator (closes #218)

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 OS user, and the state and rules directories.
The SWWAF_ environment variables take the SWW_ form.

No logic changes. make check passes.

Model: deepseek-v4-pro

internal/reputation/dnsbl_test.go

@@ -40,8 +40,8 @@ const (
 	// zone and otherZone are the DNSBL zones the tests name.
 	zone      = "dnsbl.example"
 	otherZone = "other.example"
-	// cacheTTL is the tests' SWWAF_REPUTATION_CACHE_TTL, and timeout their
-	// SWWAF_REPUTATION_TIMEOUT: a second, the least time /etc/resolv.conf
+	// cacheTTL is the tests' SWW_REPUTATION_CACHE_TTL, and timeout their
+	// SWW_REPUTATION_TIMEOUT: a second, the least time /etc/resolv.conf
 	// can have Go's resolver wait for one server, so that it is the
 	// DNSBL's own timeout that ends a query, whatever that file says.
 	cacheTTL = 24 * time.Hour
@@ -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)
 			}
@@ -419,7 +419,7 @@ func TestNeitherAVerdictOfAZoneNotNamedNorOnePastItsTTLIsKept(t *testing.T) {
 	dnsbl := reputation.NewDNSBL(p)
 
 	// The last verdict still in use, one fetched a TTL ago, and one of a
-	// zone SWWAF_DNSBL_ZONES does not name.
+	// zone SWW_DNSBL_ZONES does not name.
 	inUse := reputation.Verdict{
 		Zone: zone, Client: netip.MustParseAddr(listed), Listed: true,
 		Fetched: now.Add(-cacheTTL + time.Nanosecond),
@@ -471,7 +471,7 @@ func TestAtMost100000VerdictsKeptTheOneFetchedLongestAgoDroppedFirst(t *testing.
 }
 
 //nolint:paralleltest // one at a time, as the comment at the top of this file says
-func TestQueriesGoToTheResolverSWWAFDNSBLResolverNames(t *testing.T) {
+func TestQueriesGoToTheResolverSWWDNSBLResolverNames(t *testing.T) {
 	resolver := &resolverStandIn{answers: map[string]answer{
 		listedName: {addrs: []string{listing}},
 	}}