feat: add browse-at-scale — date ranges, load more, month navigator

CLI: --month YYYY-MM, --from/--to date range, --limit override
API: from/to query params for date range filtering
Web: load more button for pagination, month nav (◂/▸) in stream view

internal/api/entities.go

@@ -47,6 +47,20 @@ func listEntities(store *db.Store) http.HandlerFunc {
 			}
 			p.Date = &date
 		}
+		if from := r.URL.Query().Get("from"); from != "" {
+			if _, err := time.Parse("2006-01-02", from); err != nil {
+				writeError(w, http.StatusBadRequest, "invalid_input", "bad from format, use YYYY-MM-DD")
+				return
+			}
+			p.From = &from
+		}
+		if to := r.URL.Query().Get("to"); to != "" {
+			if _, err := time.Parse("2006-01-02", to); err != nil {
+				writeError(w, http.StatusBadRequest, "invalid_input", "bad to format, use YYYY-MM-DD")
+				return
+			}
+			p.To = &to
+		}
 		if r.URL.Query().Get("cards_only") == "true" {
 			p.CardsOnly = true
 		}