fix(monsters): finish deleting experienceReward, column included

Design ruling R7 abolishes XP as a concept and says the column goes with
it, but no task in the plan actually dropped it -- the plan only dropped
characters.experience and combat_rewards.experience_granted. Task 9
removed experienceReward from the seed literals, leaving
monster_definitions.experience_reward as a NOT NULL column with no
default that nothing supplies. The first monster insert against a real
database would have failed on a constraint violation.

No suite here could have caught it: none of them connect to Postgres.

Drops the column in the slice migration (which has never been run, so
amending it in place is correct rather than stacking a second one),
removes the entity field, and clears the three test fixtures that still
set it. silver_min/silver_max deliberately stay -- spec 15 keeps a
direct currency drop available as a lore-valid exception, and XP has no
such carve-out.

Also retargets the seed idempotency test off renown: 1, which is the
seed's own default and so could not distinguish "preserved" from
"reset to default".

NOTE ON SCOPE: this commit also absorbs a Prettier reformatting pass
that was already sitting uncommitted in the working tree, which is why
it touches ~59 files. That churn is purely cosmetic line-rewrapping --
verified by inspection, and the suite is green at 267/267 with the build
at exactly the 3 expected errors owned by Tasks 10 and 11. The repo is
not Prettier-clean at baseline (119 files still flagged), so this was a
partial run by an earlier step, not a deliberate repo-wide format.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/api/src/items/entities/item-definition.entity.ts

@@ -25,7 +25,12 @@ export class ItemDefinition {
   @Column({ name: 'description', type: 'text' })
   description!: string;
 
-  @Column({ name: 'type', type: 'enum', enum: ItemType, enumName: 'item_type_enum' })
+  @Column({
+    name: 'type',
+    type: 'enum',
+    enum: ItemType,
+    enumName: 'item_type_enum',
+  })
   type!: ItemType;
 
   @Column({
@@ -37,7 +42,12 @@ export class ItemDefinition {
   })
   equipmentSlot!: EquipmentSlot | null;
 
-  @Column({ name: 'rarity', type: 'enum', enum: ItemRarity, enumName: 'item_rarity_enum' })
+  @Column({
+    name: 'rarity',
+    type: 'enum',
+    enum: ItemRarity,
+    enumName: 'item_rarity_enum',
+  })
   rarity!: ItemRarity;
 
   @Column({ name: 'tier', type: 'integer' })