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/rproxy/rproxy.go

@@ -1,10 +1,10 @@
-// Package rproxy is the reverse proxy in front of one app that asks servewaf
-// about each request. It passes a request servewaf allows to the app and the
+// Package rproxy is the reverse proxy in front of one app that asks discriminator
+// about each request. It passes a request discriminator allows to the app and the
 // app's answer back, within the size and time limits. Any other answer from
-// servewaf goes to the visitor as servewaf gave it. SWRP_DEFAULT_DISPOSITION
-// decides only when servewaf cannot be connected to, does not answer at all, or
+// discriminator goes to the visitor as discriminator gave it. SWRP_DEFAULT_DISPOSITION
+// decides only when discriminator cannot be connected to, does not answer at all, or
 // does not answer within SWRP_TIMEOUT_MS. rproxy itself refuses a request with a
-// method it does not pass on, or one it cannot put to servewaf as the visitor
+// method it does not pass on, or one it cannot put to discriminator as the visitor
 // sent it. It keeps nothing between requests and never touches disk. "rproxy" in
 // SPEC.md says what it does.
 package rproxy
@@ -22,10 +22,10 @@ import (
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/config"
-	"sneak.berlin/go/smallwebwaf/internal/servewaf"
+	"sneak.berlin/go/smallwebwaf/internal/discriminator"
 )
 
-// How rproxy keeps connections to the app and to servewaf open between
+// How rproxy keeps connections to the app and to discriminator open between
 // requests.
 const (
 	idleConns       = 100
@@ -45,9 +45,9 @@ const (
 	idleTimeout = 120 * time.Second
 )
 
-// adminPrefix starts the path of every request for smallwebwaf itself, which
+// adminPrefix starts the path of every request for sww itself, which
 // never reaches the app.
-const adminPrefix = "/_smallwebwaf/"
+const adminPrefix = "/_sww/"
 
 // allowedMethods lists the methods rproxy passes on, as an Allow header gives
 // them. It answers any other method 405 itself.
@@ -62,14 +62,14 @@ type Params struct {
 	ProcessLog *slog.Logger
 }
 
-// Server is the server `smallwebwaf rproxy` runs.
+// Server is the server `sww rproxy` runs.
 type Server struct {
 	*http.Server
 
 	h *handler
 }
 
-// New returns the server `smallwebwaf rproxy` runs. Go's server itself refuses
+// New returns the server `sww rproxy` runs. Go's server itself refuses
 // a request line and headers over requestHeaderMaxBytes, with 431, closes a
 // connection idle for idleTimeout, and applies SWRP_MAX_REQUEST_TIME_MS while
 // the headers arrive. The handler applies the time and size limits from then
@@ -78,14 +78,14 @@ func New(params Params) *Server {
 	backend := params.Config.WAFBackend
 	errorLog := slog.NewLogLogger(params.ProcessLog.Handler(), slog.LevelWarn)
 	h := &handler{
-		config:            params.Config,
-		requestLog:        params.RequestLog,
-		processLog:        params.ProcessLog,
-		errorLog:          errorLog,
-		transport:         newTransport(),
-		serveWAFTransport: newServeWAFTransport(),
+		config:                 params.Config,
+		requestLog:             params.RequestLog,
+		processLog:             params.ProcessLog,
+		errorLog:               errorLog,
+		transport:              newTransport(),
+		discriminatorTransport: newDiscriminatorTransport(),
 		reportURL: (&url.URL{
-			Scheme: backend.Scheme, Host: backend.Host, Path: servewaf.ReportPath,
+			Scheme: backend.Scheme, Host: backend.Host, Path: discriminator.ReportPath,
 		}).String(),
 	}
 
@@ -120,10 +120,10 @@ type handler struct {
 	requestLog io.Writer
 	processLog *slog.Logger
 	errorLog   *log.Logger
-	// transport carries requests to the app, and serveWAFTransport questions and
-	// reports to servewaf.
-	transport         http.RoundTripper
-	serveWAFTransport http.RoundTripper
+	// transport carries requests to the app, and discriminatorTransport questions and
+	// reports to discriminator.
+	transport              http.RoundTripper
+	discriminatorTransport http.RoundTripper
 	// reportURL is where the reports go.
 	reportURL string
 	// reports waits for the reports being sent. reportsMu guards starting one
@@ -145,11 +145,11 @@ func newTransport() *http.Transport {
 	}
 }
 
-// newServeWAFTransport returns what carries questions and reports to servewaf.
-// It speaks HTTP/1.1 only. Go's HTTP/2 client refuses to send a visitor's Upgrade
-// header, or a Connection header other than close or keep-alive, and that would
-// read as servewaf giving no answer.
-func newServeWAFTransport() *http.Transport {
+// newDiscriminatorTransport returns what carries questions and reports to
+// discriminator. It speaks HTTP/1.1 only. Go's HTTP/2 client refuses to send
+// a visitor's Upgrade header, or a Connection header other than close or
+// keep-alive, and that would read as discriminator giving no answer.
+func newDiscriminatorTransport() *http.Transport {
 	transport := newTransport()
 	transport.Protocols = new(http.Protocols)
 	transport.Protocols.SetHTTP1(true)
@@ -158,15 +158,15 @@ func newServeWAFTransport() *http.Transport {
 }
 
 // ServeHTTP handles one request: it answers the health check itself, refuses a
-// request with a method it does not pass on or one it cannot put to servewaf as
+// request with a method it does not pass on or one it cannot put to discriminator as
 // the visitor sent it, and for any other request reads the first part of the
-// body, asks servewaf, and does what the answer says. Once the answer has ended,
+// body, asks discriminator, and does what the answer says. Once the answer has ended,
 // it writes the request's log line and sends its report.
 func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rq := h.newRequest(w, r)
 	defer rq.finish(r.Context())
 
-	if r.Method == http.MethodGet && r.URL.Path == servewaf.HealthPath {
+	if r.Method == http.MethodGet && r.URL.Path == discriminator.HealthPath {
 		rq.answerHealth()
 
 		return
@@ -199,9 +199,9 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rq.noteAnswer(answer)
 
 	switch rq.disposition {
-	case servewaf.DispositionAllow:
+	case discriminator.DispositionAllow:
 		rq.passToApp(r.Context())
-	case servewaf.DispositionClose:
+	case discriminator.DispositionClose:
 		// This panic has Go's server close the connection without an answer,
 		// and log nothing; the deferred finish still runs.
 		panic(http.ErrAbortHandler)
@@ -211,7 +211,7 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 // passToApp passes the request on to the app, unless a limit or its path keeps
-// it from the app. servewaf answers a path under adminPrefix itself, so such a
+// it from the app. discriminator answers a path under adminPrefix itself, so such a
 // request gets here only when SWRP_DEFAULT_DISPOSITION allowed it. ctx is the
 // request's own context.
 func (rq *request) passToApp(ctx context.Context) {