fix(utils): fall back to Intl-resolved abbreviation for unmapped timezones

getTimezoneAbbreviation only covered 9 hardcoded IANA zones and returned
the raw IANA string for everything else, degrading schedule descriptions
for zones like Europe/Berlin or America/Toronto (caught by Greptile). The
deleted local implementation in schedules/utils.ts resolved any valid IANA
timezone generically via Intl.DateTimeFormat's short timeZoneName. Restore
that as a fallback so only genuinely invalid timezone strings return
themselves unchanged.

Author: waleedlatif1

packages/utils/src/formatting.test.ts

@@ -28,6 +28,11 @@ describe('getTimezoneAbbreviation', () => {
     expect(getTimezoneAbbreviation('Unknown/Zone')).toBe('Unknown/Zone')
   })
 
+  it('resolves a valid IANA timezone outside the hardcoded map via Intl instead of the raw string', () => {
+    const result = getTimezoneAbbreviation('Europe/Berlin', new Date('2023-01-15'))
+    expect(result).not.toBe('Europe/Berlin')
+  })
+
   it('returns PST or PDT for Los Angeles', () => {
     const result = getTimezoneAbbreviation('America/Los_Angeles', new Date('2023-01-15'))
     expect(['PST', 'PDT']).toContain(result)

packages/utils/src/formatting.ts

@@ -48,7 +48,15 @@ export function getTimezoneAbbreviation(timezone: string, date: Date = new Date(
     return timezoneMap[timezone].standard
   }
 
-  return timezone
+  try {
+    const parts = new Intl.DateTimeFormat('en-US', {
+      timeZone: timezone,
+      timeZoneName: 'short',
+    }).formatToParts(date)
+    return parts.find((p) => p.type === 'timeZoneName')?.value || timezone
+  } catch {
+    return timezone
+  }
 }
 
 /**