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/waf/waf_test.go

@@ -111,7 +111,7 @@ func matched(ids ...int) waf.Result {
 	return waf.Result{RuleIDs: ids, Score: critical * len(ids)}
 }
 
-// atDefaults returns the Core Rule Set as smallwebwaf runs it by default.
+// atDefaults returns the Core Rule Set as sww runs it by default.
 func atDefaults(t *testing.T) *waf.CoreRuleSet {
 	t.Helper()
 
@@ -376,7 +376,7 @@ const (
 // injection is an SQL injection, which rule 942100 matches.
 const injection = "1' OR '1'='1"
 
-// readingBodies returns the Core Rule Set as smallwebwaf runs it by
+// readingBodies returns the Core Rule Set as sww runs it by
 // default, but reading bodies up to bodyLimit.
 func readingBodies(t *testing.T) *waf.CoreRuleSet {
 	t.Helper()