Rename the settings whose names do not say what they control (closes #234)

Applies the setting renames of the naming audit under the SWW_WAF_ and
SWW_RPROXY_ prefixes, with sneak's names for the IP reputation cache
time and the two time limits, which now take milliseconds. The rproxy
log field default_disposition becomes waf_backend_no_answer, and
config.Config and config.FromEnvironment become config.WAF and
config.WAFFromEnvironment. Go fields, test names and prose follow. No
aliases; nothing reads the old names.

Model: opus-5-5

internal/rules/rules.go

@@ -1,5 +1,5 @@
 // Package rules reads the rule files: the plain text files in
-// SWW_WAF_RULES_DIR, one rule to a line, that each request is checked
+// SWW_WAF_RULE_FILES_DIR, one rule to a line, that each request is checked
 // against, as the "Rule files" section of SPEC.md describes. They are read
 // at start, and again once the directory has had no change for a short
 // time after one is edited, added or removed.
@@ -40,7 +40,7 @@ const (
 // extension ends the name of every rule file.
 const extension = ".rules"
 
-// quietTime is how long SWW_WAF_RULES_DIR must go without a change before
+// quietTime is how long SWW_WAF_RULE_FILES_DIR must go without a change before
 // the rule files are read again, so that a file still being written, such
 // as one saved in place, appended to or copied in with scp, is read only
 // once whole.
@@ -103,9 +103,9 @@ type Rule struct {
 
 // Params are what Load needs.
 type Params struct {
-	// Dir is the directory of the rule files (SWW_WAF_RULES_DIR).
+	// Dir is the directory of the rule files (SWW_WAF_RULE_FILES_DIR).
 	Dir string
-	// Enabled is SWW_WAF_RULES_ENABLED: while it is false, no file is read
+	// Enabled is SWW_WAF_RULE_FILES_ENABLED: while it is false, no file is read
 	// and no rule loaded.
 	Enabled bool
 	// ProcessLog receives how many rules were read, and the error in a
@@ -275,7 +275,7 @@ func read(dir string) ([]Rule, string, error) {
 	entries, err := os.ReadDir(dir)
 	if err != nil {
 		return nil, dir, fmt.Errorf(
-			"SWW_WAF_RULES_DIR cannot be read: %w",
+			"SWW_WAF_RULE_FILES_DIR cannot be read: %w",
 			err,
 		)
 	}
@@ -310,7 +310,7 @@ func readFile(
 	rules []Rule,
 	places map[string]string,
 ) ([]Rule, error) {
-	//nolint:gosec // a rule file, in SWW_WAF_RULES_DIR
+	//nolint:gosec // a rule file, in SWW_WAF_RULE_FILES_DIR
 	data, err := os.ReadFile(path)
 	if err != nil {
 		return nil, err