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/reputation/abuseipdb.go

@@ -58,17 +58,17 @@ type Checks struct {
 // AbuseIPDBParams are what NewAbuseIPDB needs.
 type AbuseIPDBParams struct {
 	// URL is where clients are checked, normally AbuseIPDBURL, with Key,
-	// the account's key (SWWAF_ABUSEIPDB_KEY).
+	// the account's key (SWW_ABUSEIPDB_KEY).
 	URL string
 	Key string
-	// MinScore is the least score that is a hit (SWWAF_ABUSEIPDB_MIN_SCORE),
+	// MinScore is the least score that is a hit (SWW_ABUSEIPDB_MIN_SCORE),
 	// and DailyBudget the most checks made in a day, in UTC
-	// (SWWAF_ABUSEIPDB_DAILY_BUDGET).
+	// (SWW_ABUSEIPDB_DAILY_BUDGET).
 	MinScore    int64
 	DailyBudget int
 	// CacheTTL is how long a score is used after it was fetched
-	// (SWWAF_REPUTATION_CACHE_TTL), and Timeout how long a check may take
-	// (SWWAF_REPUTATION_TIMEOUT).
+	// (SWW_REPUTATION_CACHE_TTL), and Timeout how long a check may take
+	// (SWW_REPUTATION_TIMEOUT).
 	CacheTTL time.Duration
 	Timeout  time.Duration
 	// Now tells the time, normally time.Now in UTC.