Remove everything specific to a Gitea deployment (closes #209)

Delete the Gitea compose setup, its document, its two scripts and their
make targets. Drop the Core Rule Set exclusions written for Gitea: the
ten query parameters skipped by rules 930120, 932160 and 932260, and the
gitea_flash and redirect_to cookies. The remaining changes are
renumbered, five in all. Documents and tests use neutral examples.

Model: opus-5-5

internal/requestlog/requestlog_test.go

@@ -94,7 +94,7 @@ func TestProcessLinesAreMarkedProcessAndGiveTheInstance(t *testing.T) {
 
 	var out bytes.Buffer
 
-	requestlog.NewProcessLogger(&out, "fsn1app1/gitea", slog.LevelInfo).Info("starting",
+	requestlog.NewProcessLogger(&out, "fsn1app1/blog", slog.LevelInfo).Info("starting",
 		"version", "v1")
 
 	var fields map[string]any
@@ -104,7 +104,7 @@ func TestProcessLinesAreMarkedProcessAndGiveTheInstance(t *testing.T) {
 		t.Fatalf("decode %q: %v", out.String(), err)
 	}
 
-	if fields["type"] != "process" || fields["instance"] != "fsn1app1/gitea" ||
+	if fields["type"] != "process" || fields["instance"] != "fsn1app1/blog" ||
 		fields["msg"] != "starting" || fields["level"] != "INFO" ||
 		fields["version"] != "v1" {
 		t.Errorf("process line %v", fields)
@@ -133,7 +133,7 @@ func TestProcessLoggerWritesTheMessagesAtItsLevelOrMoreSevere(t *testing.T) {
 
 			var out bytes.Buffer
 
-			processLog := requestlog.NewProcessLogger(&out, "fsn1app1/gitea", level)
+			processLog := requestlog.NewProcessLogger(&out, "fsn1app1/blog", level)
 			for _, at := range levels {
 				processLog.Log(t.Context(), at, "message")
 			}