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/reputation/dnsbl.go

@@ -53,15 +53,15 @@ type Verdict struct {
 // DNSBLParams are what NewDNSBL needs.
 type DNSBLParams struct {
 	// Zones are the DNSBL zones clients are asked about in
-	// (SWW_DNSBL_ZONES).
+	// (SWW_WAF_DNSBL_ZONES).
 	Zones []string
 	// Resolver is the resolver they are asked through
-	// (SWW_DNSBL_RESOLVER), or, while it is the zero AddrPort, the
+	// (SWW_WAF_DNSBL_RESOLVER), or, while it is the zero AddrPort, the
 	// host's, as /etc/resolv.conf names it.
 	Resolver netip.AddrPort
 	// CacheTTL is how long a verdict is used after it was fetched
-	// (SWW_REPUTATION_CACHE_TTL), and Timeout how long a query may take
-	// (SWW_REPUTATION_TIMEOUT).
+	// (SWW_WAF_REPUTATION_CACHE_TTL), and Timeout how long a query may take
+	// (SWW_WAF_REPUTATION_TIMEOUT).
 	CacheTTL time.Duration
 	Timeout  time.Duration
 	// Now tells the time, normally time.Now in UTC.
@@ -127,13 +127,13 @@ func NewDNSBL(params DNSBLParams) *DNSBL {
 	}
 }
 
-// Zones returns the zones, in the order SWW_DNSBL_ZONES names them.
+// Zones returns the zones, in the order SWW_WAF_DNSBL_ZONES names them.
 func (d *DNSBL) Zones() []string {
 	return slices.Clone(d.params.Zones)
 }
 
 // ListedBy returns the zones whose verdict on addr, a client's address,
-// lists it, in the order SWW_DNSBL_ZONES names them, each with its key
+// lists it, in the order SWW_WAF_DNSBL_ZONES names them, each with its key
 // masked, as config.MaskZoneKey masks it, since they go to the request
 // log, the alerts and the metrics. A verdict is used until CacheTTL has
 // passed since it was fetched. Each zone without one is asked about addr
@@ -210,7 +210,7 @@ func (d *DNSBL) Snapshot() []Verdict {
 }
 
 // Load keeps verdicts, read from reputation.json, in place of those it
-// keeps, but for those of a zone SWW_DNSBL_ZONES does not name, and,
+// keeps, but for those of a zone SWW_WAF_DNSBL_ZONES does not name, and,
 // past maxVerdicts, those fetched longest ago. One fetched CacheTTL ago or
 // more is neither used nor written, as for any verdict.
 func (d *DNSBL) Load(verdicts []Verdict) {