feat: implement revision retention settings and pruning logic

Added functionality to handle revision retention minutes in global settings, including validation for input values. Introduced a new method to prune old revisions based on the specified retention period, ensuring that only the most recent revisions are kept. Updated the frontend to allow users to configure the revision retention setting, enhancing the management of revision lifecycles.

internal/httpapi/routes_crud.go

@@ -1142,9 +1142,47 @@ func (s *Server) handlePatchSettings(w http.ResponseWriter, r *http.Request) {
 		writeProblem(w, http.StatusBadRequest, "Bad Request", "invalid json")
 		return
 	}
+	if raw, ok := body["revision_retention_minutes"]; ok && raw != nil {
+		v, ok := parseRevisionRetentionMinutes(raw)
+		if !ok {
+			writeProblem(w, http.StatusUnprocessableEntity, "Unprocessable Entity", "revision_retention_minutes must be an integer in range 15..43200")
+			return
+		}
+		body["revision_retention_minutes"] = v
+	}
 	if err := s.store.PatchGlobalSettings(a.TenantID, body); err != nil {
 		writeStoreErr(w, err)
 		return
 	}
 	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
 }
+
+func parseRevisionRetentionMinutes(v any) (int, bool) {
+	const minMinutes = 15
+	const maxMinutes = 30 * 24 * 60
+
+	var out int
+	switch x := v.(type) {
+	case float64:
+		if x != float64(int(x)) {
+			return 0, false
+		}
+		out = int(x)
+	case int:
+		out = x
+	case int64:
+		out = int(x)
+	case string:
+		n, err := strconv.Atoi(strings.TrimSpace(x))
+		if err != nil {
+			return 0, false
+		}
+		out = n
+	default:
+		return 0, false
+	}
+	if out < minMinutes || out > maxMinutes {
+		return 0, false
+	}
+	return out, true
+}