fix: remove duplicate addDays utility (#2059)

Author: graphieros

app/utils/charts.ts

@@ -32,12 +32,6 @@ export function buildWeeklyEvolutionFromDaily(
   })
 }
 
-export function addDays(date: Date, days: number): Date {
-  const d = new Date(date)
-  d.setUTCDate(d.getUTCDate() + days)
-  return d
-}
-
 // Statistics & Interpretation utilities
 
 export function clamp(value: number, minValue: number, maxValue: number): number {

test/unit/app/utils/charts.spec.ts

@@ -3,7 +3,6 @@ import {
   sum,
   chunkIntoWeeks,
   buildWeeklyEvolutionFromDaily,
-  addDays,
   clamp,
   quantile,
   winsorize,
@@ -325,59 +324,6 @@ describe('buildWeeklyEvolutionFromDaily', () => {
   })
 })
 
-describe('addDays', () => {
-  it('returns a new Date instance (does not mutate original)', () => {
-    const original = new Date('2028-01-01T00:00:00Z')
-    const result = addDays(original, 5)
-
-    expect(result).not.toBe(original)
-    expect(original.toISOString()).toBe('2028-01-01T00:00:00.000Z')
-  })
-
-  it('adds positive days correctly', () => {
-    const date = new Date('2028-01-01T00:00:00Z')
-    const result = addDays(date, 10)
-
-    expect(result.toISOString()).toBe('2028-01-11T00:00:00.000Z')
-  })
-
-  it('subtracts days when negative value is provided', () => {
-    const date = new Date('2028-01-10T00:00:00Z')
-    const result = addDays(date, -5)
-
-    expect(result.toISOString()).toBe('2028-01-05T00:00:00.000Z')
-  })
-
-  it('handles month overflow correctly', () => {
-    const date = new Date('2028-01-28T00:00:00Z')
-    const result = addDays(date, 5)
-
-    expect(result.toISOString()).toBe('2028-02-02T00:00:00.000Z')
-  })
-
-  it('handles year overflow correctly', () => {
-    const date = new Date('2027-12-29T00:00:00Z')
-    const result = addDays(date, 5)
-
-    expect(result.toISOString()).toBe('2028-01-03T00:00:00.000Z')
-  })
-
-  it('handles leap year correctly', () => {
-    const date = new Date('2028-02-27T00:00:00Z') // 2028 is leap year
-    const result = addDays(date, 2)
-
-    expect(result.toISOString()).toBe('2028-02-29T00:00:00.000Z')
-  })
-
-  it('keeps UTC behavior consistent (no timezone drift)', () => {
-    const date = new Date('2028-03-01T00:00:00Z')
-    const result = addDays(date, 1)
-
-    expect(result.getUTCHours()).toBe(0)
-    expect(result.toISOString()).toBe('2028-03-02T00:00:00.000Z')
-  })
-})
-
 describe('clamp', () => {
   it('returns the value when it is within bounds', () => {
     expect(clamp(5, 0, 10)).toBe(5)