refactor: rename "recurring" to "week overview"

refactor: replace dashboard calendar icon
resolves #128

refactor: route dashboard "next unit" to date series instead of events
resolves #126

frontend/app/src/assets/i18n/de.json

@@ -459,9 +459,9 @@
     "view": {
       "today": "Heute"
     },
-    "recurring": "Stundenplan",
+    "recurring": "Wochen­übersicht",
     "calendar": "Kalender",
-    "single": "Einzeltermine",
+    "single": "Einzel­termine",
     "addEventPage": {
       "TITLE": "Termine Hinzufügen",
       "PLACEHOLDER": "Termine",

frontend/app/src/assets/i18n/en.json

@@ -459,7 +459,7 @@
     "view": {
       "today": "Today"
     },
-    "recurring": "Recurring",
+    "recurring": "Week Overview",
     "calendar": "Calendar",
     "single": "Single Events",
     "addEventPage": {