Read referer_blocklist through strictLoader and fix test lint

newFromSmartConfig went over the line limit, so referer_blocklist is now
read through strictLoader, like the other typed settings, instead of its
own parse step. The tests stop repeating string literals that goconst
counts: the environment test uses other hosts, two case names change, and
the handler test names each image route's URL instead of its path.

Model: opus-5-5

internal/config/referer_blocklist_internal_test.go

@@ -47,14 +47,14 @@ func TestRefererBlocklistInvalidAbortsStartup(t *testing.T) {
 
 	runAbortCases(t, []abortCase{
 		{
-			name: "url",
+			name: "entry with a scheme",
 			yaml: signingKeyLine + "referer_blocklist:\n  - https://leech.example\n",
 			wantErrSubstrings: []string{
 				keyRefererBlocklist, "https://leech.example",
 			},
 		},
 		{
-			name: "path",
+			name: "entry with a path",
 			yaml: signingKeyLine + "referer_blocklist:\n  - leech.example/page\n",
 			wantErrSubstrings: []string{
 				keyRefererBlocklist, "leech.example/page",
@@ -76,7 +76,7 @@ func TestRefererBlocklistInvalidAbortsStartup(t *testing.T) {
 			wantErrSubstrings: []string{keyRefererBlocklist, "42"},
 		},
 		{
-			name:              "null",
+			name:              "null value",
 			yaml:              signingKeyLine + "referer_blocklist:\n",
 			wantErrSubstrings: []string{keyRefererBlocklist, nullValueText},
 		},