feat(calendar): add explained period feature and update translations

src/app/components/calendar-year/calendar-year.scss

@@ -369,10 +369,6 @@ output {
 	justify-items: start;
 	gap: 0.75rem;
 }
-.counterfactual-progress {
-	color: var(--ui-text-secondary);
-	font-size: 0.875rem;
-}
 .decisive-summary {
 	padding: 0.75rem;
 	border-inline-start: 3px solid var(--mat-sys-primary);
@@ -442,6 +438,13 @@ output {
 	&.today {
 		border: 2px dashed var(--today-border-color);
 	}
+	&.current {
+		outline: 2px solid var(--today-border-color);
+		outline-offset: -2px;
+	}
+	&.explained-period {
+		box-shadow: inset 0 -3px var(--today-border-color);
+	}
 }
 .legend-symbol,
 .status-symbol {