feat(03-01): add CSS animation tokens, i18n keys, and carryover display

- Add collapsible-open/close keyframes and CSS animation tokens to index.css
- Add dashboard.sections and dashboard.carryoverIncludes keys to en.json and de.json
- Add optional subtitle/subtitleClassName props to StatCard
- Extend SummaryStrip balance prop with carryoverSubtitle/carryoverIsNegative
- Compute and pass carryover subtitle from DashboardContent to SummaryStrip

src/i18n/de.json

@@ -84,7 +84,12 @@
     "actual": "Tatsaechlich",
     "noBudgetForMonth": "Kein Budget fuer diesen Monat",
     "createBudget": "Budget erstellen",
-    "generateFromTemplate": "Aus Vorlage generieren"
+    "generateFromTemplate": "Aus Vorlage generieren",
+    "sections": {
+      "itemName": "Posten",
+      "groupTotal": "{{label}} Gesamt"
+    },
+    "carryoverIncludes": "Inkl. {{amount}} Übertrag"
   },
   "quickAdd": {
     "title": "Schnelleingabe-Bibliothek",

src/i18n/en.json

@@ -84,7 +84,12 @@
     "actual": "Actual",
     "noBudgetForMonth": "No budget for this month",
     "createBudget": "Create Budget",
-    "generateFromTemplate": "Generate from Template"
+    "generateFromTemplate": "Generate from Template",
+    "sections": {
+      "itemName": "Item",
+      "groupTotal": "{{label}} Total"
+    },
+    "carryoverIncludes": "Includes {{amount}} carryover"
   },
   "quickAdd": {
     "title": "Quick Add Library",