Prayer: bury on the spot, retuned costs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -145,11 +145,13 @@ Beta. The core game is in place; changes from here are mostly balance and tuning
   them a day, so it slows as the houses fill, plus slow family growth); it promotes the settlement
   (hamlet, village at 40, town at 90, city at 150), which raises building
   level caps and gives everyone bank slots.
-- **Prayer:** enemies drop bones; burying them gives prayer points and
-  Prayer XP. Up to two prayers (eight unlock from level 1 to 60) boost each
-  fight while their points last, and praying trains Prayer too. A Temple adds
-  points per bone and lets players offer bones as devotion, which wards the
-  city in the next raid.
+- **Prayer:** enemies drop bones, which are buried on the spot for prayer
+  points and half the XP of burying by hand (a setting; off sends them to
+  the bank, to bury by hand for full XP). Up to two prayers (eight unlock from level 1 to 60) boost each
+  fight while their points last, and praying trains Prayer. Early in each
+  bone tier bones cover two prayers; later a Prayer potion makes up the gap.
+  A Temple adds 25% points from bones a level and lets players offer bones as
+  devotion, which wards the city in the next raid.
 - **Herblore:** farmers grow six herbs (guam to snapdragon), one per tier.
   Every potion is a ladder of up to six tiers (I–VI): the tier's herb plus
   the matching rung of the skill's own resources (copper ore → runite ore,