Fix Cache-Control s-maxage in Streak Route Using Computed secondsToMidnight (JhaSourav07#8172)

* fix: use computed secondsToMidnight in streak route Cache-Control s-maxage

The route computed secondsToMidnight using getSecondsUntilMidnightInTimezone /
getSecondsUntilUTCMidnight but hardcoded s-maxage=1 in both the JSON and SVG
response paths. This caused CDN cache to expire every 1 second regardless of
timezone and made the timezone-boundaries test suite fail.

Replace hardcoded s-maxage=1 with the computed value in both paths. Also fix 3
test assertions in route.test.ts that were asserting the broken behavior.

Fixes JhaSourav07#8170

* chore: trigger CI rerun

* test: fix timezone boundary tests to expect correct s-maxage

Author: Aamod007

app/api/streak/route.timezone-boundaries.test.ts

@@ -89,7 +89,7 @@ describe('ApiStreakRoute Timezone Normalization & Calendar Boundary Alignment',
     expect(getSecondsUntilMidnightInTimezone).toHaveBeenCalled();
     expect(getSecondsUntilUTCMidnight).not.toHaveBeenCalled();
 
-    expect(response.headers.get('Cache-Control')).toContain('s-maxage=1');
+    expect(response.headers.get('Cache-Control')).toContain('s-maxage=7200');
   });
 
   it('returns 400 for an invalid timezone and skips GitHub fetching', async () => {
@@ -123,7 +123,7 @@ describe('ApiStreakRoute Timezone Normalization & Calendar Boundary Alignment',
 
     expect(response.status).toBe(200);
 
-    expect(response.headers.get('Cache-Control')).toContain('s-maxage=1');
+    expect(response.headers.get('Cache-Control')).toContain('s-maxage=1234');
 
     const body = await response.json();