fix(constants): Bump default fillDeadline 2.5 -> 3.25 hours (#1416)

2.5 hours has proven to be a little bit too tight. So far there have
been 3 large deposits that timed out shortly before slow fills could be
executed. Analysis of these fills shows that even 3 hours would have
been tight (but not impossible). Conservatively default to 3.25 hours
instead. To be updated in the event that dart request a different
number.

api/_constants.ts

@@ -209,4 +209,4 @@ export const DEFAULT_LITE_CHAIN_USD_MAX_BALANCE = "250000";
 
 export const DEFAULT_LITE_CHAIN_USD_MAX_DEPOSIT = "25000";
 
-export const DEFAULT_FILL_DEADLINE_BUFFER_SECONDS = 2.5 * 60 * 60; // 2.5 hours
+export const DEFAULT_FILL_DEADLINE_BUFFER_SECONDS = 3.25 * 60 * 60; // 3.25 hours