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 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/abuseipdb_test.go

@@ -397,7 +397,7 @@ func TestMetricsCountTheChecksTheFailuresAndTheBudgetLeft(t *testing.T) {
 			"failures_total":         "1",
 			"daily_budget_remaining": "3",
 		} {
-			line := "\nsmallwebwaf_reputation_" + series +
+			line := "\nsww_reputation_" + series +
 				`{instance="app",source="abuseipdb"} ` + want + "\n"
 			if !strings.Contains(scraped, line) {
 				t.Errorf("metrics\n%s\nwant%s", scraped, line)
@@ -581,7 +581,7 @@ func wantScore(
 
 // hitFrom is checker's Hit for a request from address, offender or not.
 // Its client is address for an IPv4 address, and its /64 for an IPv6 one,
-// as smallwebwaf counts clients.
+// as sww counts clients.
 func hitFrom(
 	t *testing.T, checker *reputation.AbuseIPDB, address string, offender bool,
 ) (int64, bool) {