feat(06-02): add preset i18n translations to en.json and de.json

- Add top-level presets key with presets.{type}.{slug} structure
- 19 English translations covering all 6 category types
- 19 German translations covering all 6 category types
- Both JSON files remain valid after edits

src/i18n/de.json

@@ -120,5 +120,38 @@
     "loading": "Laden...",
     "error": "Etwas ist schiefgelaufen",
     "confirm": "Bestätigen"
+  },
+  "presets": {
+    "income": {
+      "salary": "Gehalt",
+      "freelance": "Freelance-Einkommen",
+      "rental_income": "Mieteinnahmen",
+      "other_income": "Sonstiges Einkommen"
+    },
+    "bill": {
+      "rent": "Miete",
+      "electricity": "Strom",
+      "internet": "Internet",
+      "phone": "Telefon"
+    },
+    "variable_expense": {
+      "groceries": "Lebensmittel",
+      "transport": "Transport",
+      "dining_out": "Auswärts essen",
+      "health": "Gesundheit & Apotheke",
+      "clothing": "Kleidung"
+    },
+    "debt": {
+      "loan_repayment": "Kreditrückzahlung",
+      "credit_card": "Kreditkarte"
+    },
+    "saving": {
+      "emergency_fund": "Notfallfonds",
+      "vacation": "Urlaubskasse"
+    },
+    "investment": {
+      "etf": "ETF / Indexfonds",
+      "pension": "Altersvorsorge"
+    }
   }
 }

src/i18n/en.json

@@ -120,5 +120,38 @@
     "loading": "Loading...",
     "error": "Something went wrong",
     "confirm": "Confirm"
+  },
+  "presets": {
+    "income": {
+      "salary": "Salary",
+      "freelance": "Freelance Income",
+      "rental_income": "Rental Income",
+      "other_income": "Other Income"
+    },
+    "bill": {
+      "rent": "Rent",
+      "electricity": "Electricity",
+      "internet": "Internet",
+      "phone": "Phone"
+    },
+    "variable_expense": {
+      "groceries": "Groceries",
+      "transport": "Transport",
+      "dining_out": "Dining Out",
+      "health": "Health & Pharmacy",
+      "clothing": "Clothing"
+    },
+    "debt": {
+      "loan_repayment": "Loan Repayment",
+      "credit_card": "Credit Card"
+    },
+    "saving": {
+      "emergency_fund": "Emergency Fund",
+      "vacation": "Vacation Fund"
+    },
+    "investment": {
+      "etf": "ETF / Index Fund",
+      "pension": "Pension"
+    }
   }
 }