feat: add finance module with yearly income/expense tracking

- FinanceEntry model (income/expense x fixed/extra)
- CRUD API endpoints for finance entries
- FinancePage with summary cards and drill-down
- Updated navigation with Finance tab
- Updated todos default filter to active

internal/repository/repository.go

@@ -76,3 +76,35 @@ func (r *DailyLogRepository) Upsert(log *model.DailyLog) error {
 	existing.Evening = log.Evening
 	return r.db.Save(&existing).Error
 }
+
+type FinanceRepository struct {
+	db *gorm.DB
+}
+
+func NewFinanceRepository(db *gorm.DB) *FinanceRepository {
+	return &FinanceRepository{db: db}
+}
+
+func (r *FinanceRepository) GetByYear(year int) ([]model.FinanceEntry, error) {
+	var entries []model.FinanceEntry
+	err := r.db.Where("year = ?", year).Order("month ASC, id ASC").Find(&entries).Error
+	return entries, err
+}
+
+func (r *FinanceRepository) Create(entry *model.FinanceEntry) error {
+	return r.db.Create(entry).Error
+}
+
+func (r *FinanceRepository) Update(entry *model.FinanceEntry) error {
+	return r.db.Save(entry).Error
+}
+
+func (r *FinanceRepository) Delete(id uint64) error {
+	return r.db.Delete(&model.FinanceEntry{}, id).Error
+}
+
+func (r *FinanceRepository) GetByID(id uint64) (*model.FinanceEntry, error) {
+	var entry model.FinanceEntry
+	err := r.db.First(&entry, id).Error
+	return &entry, err
+}