fix(timezone): compare locations by name instead of pointer

Pointer comparison would miss equivalent locations loaded
independently, causing an unnecessary t.In() call.

internal/timezone/timezone.go

@@ -487,7 +487,7 @@ func Convert(tz string, t time.Time) time.Time {
 			t.Nanosecond(),
 			userTimezone,
 		)
-	} else if t.Location() != userTimezone {
+	} else if t.Location().String() != userTimezone.String() {
 		return t.In(userTimezone)
 	}
 

internal/timezone/timezone_test.go

@@ -77,6 +77,19 @@ func TestConvertTimeWithIdenticalTimezone(t *testing.T) {
 	}
 }
 
+func TestConvertTimeWithEquivalentTimezone(t *testing.T) {
+	tz := "UTC"
+	// FixedZone creates a distinct pointer that has the same name as the cached location.
+	// The old pointer comparison would treat these as different, calling t.In() unnecessarily.
+	loc := time.FixedZone("UTC", 0)
+	input := time.Date(2024, 6, 15, 12, 0, 0, 0, loc)
+	output := Convert(tz, input)
+
+	if output.Location() != loc {
+		t.Fatal("Convert replaced the location even though timezone names match")
+	}
+}
+
 func TestConvertPostgresDateTimeWithNegativeTimezoneOffset(t *testing.T) {
 	tz := "US/Eastern"
 	input := time.Date(0, 1, 1, 0, 0, 0, 0, time.FixedZone("", -5))