fix(cron): keep the scheduler alive when a job errors

Registered jobs are third party callbacks and were invoked bare. An error inside
one propagates out of OnTime into Tick, so Tick never reaches its
SetTimeout(60000, Tick) at the end and nothing ever reschedules it. From that
moment cron is dead for every resource on the server - paychecks, cleanups,
anything registered through cron:runAt - until a restart. The operator sees one
stack trace and then silence.

Wrapping the callback keeps the loop and the reschedule intact, and names the job
that failed.

Simulated the scheduler chain in standalone Lua with three jobs where the first
raises: before, the tick died before SetTimeout and the two later jobs never ran
again; after, the failure is reported and both later jobs fire.

[core]/cron/server/main.lua

@@ -38,7 +38,10 @@ function OnTime(timestamp)
 
         if timestamp >= scheduledTimestamp and (not lastTimestamp or lastTimestamp < scheduledTimestamp) then
             local d = os.date('*t', scheduledTimestamp).wday
-            cronJobs[i].cb(d, cronJobs[i].h, cronJobs[i].m)
+
+            if not pcall(cronJobs[i].cb, d, cronJobs[i].h, cronJobs[i].m) then
+                print(("[^1ERROR^7] cron job at ^5%02d:%02d^7 errored, skipping it"):format(cronJobs[i].h, cronJobs[i].m))
+            end
         end
     end
 end