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/bans/admin_test.go

@@ -33,7 +33,7 @@ func TestAdminsBansAreNeverDroppedAndDoNotCountTowardMaxBans(t *testing.T) {
 	third := netip.MustParsePrefix("203.0.113.3/32")
 
 	// Seen longest ago, a netblock with two of an admin's bans alone, and
-	// then one with an admin's ban before a ban smallwebwaf made: the one
+	// then one with an admin's ban before a ban sww made: the one
 	// ban counted toward MaxBans.
 	ledger.Load([]bans.Ban{
 		{Netblock: adminsOnly, Start: midnight().Add(-3 * time.Hour), Cause: bans.CauseAdmin},
@@ -48,7 +48,7 @@ func TestAdminsBansAreNeverDroppedAndDoNotCountTowardMaxBans(t *testing.T) {
 	})
 	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 2})
 
-	// A new ban drops the ban smallwebwaf made, and only that one.
+	// A new ban drops the ban sww made, and only that one.
 	ledger.BanForLimit(second, midnight(), bans.Notes{})
 	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 1, second: 1})
 
@@ -114,7 +114,7 @@ func TestEarlierBansCountABanAnAdminKeepsOnce(t *testing.T) {
 	}
 }
 
-func TestReasonOfTheBansSmallwebwafMakes(t *testing.T) {
+func TestReasonOfTheBansSwwMakes(t *testing.T) {
 	t.Parallel()
 
 	ledger := bans.New(defaultRules())
@@ -226,7 +226,7 @@ func TestLoadEditCountsTheBansAnAdminMade(t *testing.T) {
 		t.Fatalf("%d bans made by an admin after the start's, want none", got)
 	}
 
-	// The admin keeps the ban smallwebwaf made, keeps the one read at the
+	// The admin keeps the ban sww made, keeps the one read at the
 	// start, and adds one without a cause: that one alone is made.
 	kept := made
 	kept.Cause = bans.CauseAdmin