Read every setting through viper and rename the settings (closes #211)

Every setting of discriminator and rproxy is read through viper, in place
of the os.LookupEnv function Main passed down. NewViper turns AutomaticEnv
and AllowEmptyEnv on, so a setting that is set but empty reads as set. A
setting may also be given as a file, the _FILE form, which rproxy's
settings now have too; rproxy still writes nothing to disk.

The settings are renamed. Discriminator's take the prefix SWW_WAF_,
rproxy's take SWW_RPROXY_, and the shared SWW_COMMAND keeps SWW_. The Core
Rule Set's settings take SWW_WAF_CORE_RULE_SET_ rather than SWW_WAF_WAF_.
Every place a name appeared changed: the code, the viper keys, tests,
documents, examples, the README's settings table and the image files.

Model: deepseek-v4-pro

internal/rproxy/request.go

@@ -50,10 +50,10 @@ type request struct {
 	start       time.Time
 
 	// disposition is what is done with the request: discriminator's valid disposition,
-	// or SWRP_DEFAULT_DISPOSITION. It is "" when neither gave one.
+	// or SWW_RPROXY_DEFAULT_DISPOSITION. It is "" when neither gave one.
 	disposition string
 	// answered is true when discriminator gave disposition, which makes a report due,
-	// and byDefault when SWRP_DEFAULT_DISPOSITION did.
+	// and byDefault when SWW_RPROXY_DEFAULT_DISPOSITION did.
 	answered  bool
 	byDefault bool
 	// asn and country are discriminator's X-Client-ASN and X-Client-Country, for the
@@ -118,10 +118,10 @@ func (rq *request) answerHealth() {
 }
 
 // readFirstPartOfBody reads up to the first 64 KiB of the body into memory,
-// within SWRP_MAX_REQUEST_TIME_MS, and reports whether the request goes on. A
+// within SWW_RPROXY_MAX_REQUEST_TIME_MS, and reports whether the request goes on. A
 // visitor too slow to send it is answered 408. For a malformed chunk, or a
 // visitor that went away or stopped its sending side, the connection is closed
-// without an answer. A body over SWRP_MAX_REQUEST_SIZE goes on with the part
+// without an answer. A body over SWW_RPROXY_MAX_REQUEST_SIZE goes on with the part
 // read, so that discriminator is asked first; passToApp then refuses it.
 func (rq *request) readFirstPartOfBody() bool {
 	if rq.body == nil {
@@ -190,7 +190,7 @@ func (rq *request) forward(ctx context.Context) {
 }
 
 // rewrite makes the request the app receives: the visitor's request, unchanged,
-// sent to SWRP_UPSTREAM_URL, with the forwarded headers and the request's id set,
+// sent to SWW_RPROXY_UPSTREAM_URL, with the forwarded headers and the request's id set,
 // without any X-Client-ASN or X-Client-Country the visitor sent, and with
 // discriminator's.
 func (rq *request) rewrite(pr *httputil.ProxyRequest) {
@@ -325,7 +325,7 @@ func (rq *request) send(status int, body []byte) {
 
 // prepareOwnAnswer readies the connection for an answer rproxy gives itself: the
 // reading of a body that has not arrived whole ends at deadline, and the answer
-// has SWRP_MAX_RESPONSE_TIME_MS from now to reach the visitor, even when the app
+// has SWW_RPROXY_MAX_RESPONSE_TIME_MS from now to reach the visitor, even when the app
 // used that time up first.
 func (rq *request) prepareOwnAnswer(deadline time.Time) {
 	rq.stopReadingBody(deadline)
@@ -419,7 +419,7 @@ func (rq *request) bytesEachWay() (int64, int64) {
 }
 
 // requestDeadline is when the visitor must have sent its whole request, or zero
-// when SWRP_MAX_REQUEST_TIME_MS is off.
+// when SWW_RPROXY_MAX_REQUEST_TIME_MS is off.
 func (rq *request) requestDeadline() time.Time {
 	limit := rq.h.config.MaxRequestTime
 	if limit == 0 {
@@ -440,7 +440,7 @@ func (rq *request) stopReadingBody(deadline time.Time) {
 	_ = rq.rc.SetReadDeadline(deadline)
 }
 
-// startRequestTimer starts SWRP_MAX_REQUEST_TIME_MS, which runs from the
+// startRequestTimer starts SWW_RPROXY_MAX_REQUEST_TIME_MS, which runs from the
 // request's headers being read until the app has been sent the whole request.
 func (rq *request) startRequestTimer() {
 	deadline := rq.requestDeadline()
@@ -454,7 +454,7 @@ func (rq *request) startRequestTimer() {
 	rq.requestTimer = time.AfterFunc(time.Until(deadline), rq.requestTimedOut)
 }
 
-// requestTimedOut is called when SWRP_MAX_REQUEST_TIME_MS runs out while the
+// requestTimedOut is called when SWW_RPROXY_MAX_REQUEST_TIME_MS runs out while the
 // request is still on its way to the app. The answer names the side rproxy was
 // waiting on at that moment: 408 when it was waiting for the visitor to send more
 // of its body, 504 when it was waiting for the app to be reached or to take what
@@ -500,7 +500,7 @@ func (rq *request) gotFirstResponseByte() {
 }
 
 // wroteRequest is called once the app has been sent the whole request:
-// SWRP_MAX_REQUEST_TIME_MS ends and SWRP_MAX_RESPONSE_TIME_MS starts.
+// SWW_RPROXY_MAX_REQUEST_TIME_MS ends and SWW_RPROXY_MAX_RESPONSE_TIME_MS starts.
 func (rq *request) wroteRequest(info httptrace.WroteRequestInfo) {
 	if info.Err != nil {
 		return // the transport gives up, or tries again
@@ -524,7 +524,7 @@ func (rq *request) wroteRequest(info httptrace.WroteRequestInfo) {
 	}
 }
 
-// responseTimedOut is called when SWRP_MAX_RESPONSE_TIME_MS runs out before the
+// responseTimedOut is called when SWW_RPROXY_MAX_RESPONSE_TIME_MS runs out before the
 // app has sent its whole answer.
 func (rq *request) responseTimedOut() {
 	rq.mu.Lock()
@@ -539,7 +539,7 @@ func (rq *request) responseTimedOut() {
 // answer before the visitor has sent its whole body, as with a 404 it sends
 // without reading it. The time limits then run on: until the transport's read of
 // the body returns, Go's server cannot send the answer, and
-// SWRP_MAX_REQUEST_TIME_MS is what ends that read for a visitor that stops
+// SWW_RPROXY_MAX_REQUEST_TIME_MS is what ends that read for a visitor that stops
 // sending.
 func (rq *request) responseReceived() {
 	if rq.body != nil && !rq.body.received.Load() {
@@ -549,7 +549,7 @@ func (rq *request) responseReceived() {
 	rq.stopTimers()
 }
 
-// setResponseDeadline sets SWRP_MAX_RESPONSE_TIME_MS on the connection to the
+// setResponseDeadline sets SWW_RPROXY_MAX_RESPONSE_TIME_MS on the connection to the
 // visitor: the app's answer must reach the visitor within it of the end of the
 // request.
 func (rq *request) setResponseDeadline() {