feat(guild): persist weekly bonus exceptional user count

The handler was a stub that discarded pkt.NumUsers. Now it
looks up the player's guild and atomically accumulates the
count via a new weekly_bonus_users column on the guilds table.

schemas/patch-schema/29-guild-weekly-bonus.sql

@@ -0,0 +1,6 @@
+BEGIN;
+
+ALTER TABLE IF EXISTS public.guilds
+    ADD COLUMN IF NOT EXISTS weekly_bonus_users INT NOT NULL DEFAULT 0;
+
+END;