feat(budget): gelir planı ve günlük plan

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/models/budget.ts

@@ -12,11 +12,21 @@ const limitSchema = new Schema(
   { _id: false },
 );
 
+/** Gelir planına elle eklenen beklenen gelir (planlı işlemi olmayan, ör. prim). */
+const incomeItemSchema = new Schema(
+  {
+    name: { type: String, required: true, trim: true, maxlength: 80 },
+    amountMinor: { type: Number, required: true, min: 1 },
+  },
+  { _id: true },
+);
+
 const budgetSchema = new Schema(
   {
     householdId: { type: Schema.Types.ObjectId, required: true },
     month: { type: String, required: true, match: /^\d{4}-(0[1-9]|1[0-2])$/ },
     limits: { type: [limitSchema], default: [] },
+    incomeItems: { type: [incomeItemSchema], default: [] },
     seedRef: { type: String, default: null },
     createdBy: { type: Schema.Types.ObjectId, required: true },
     updatedBy: { type: Schema.Types.ObjectId, required: true },