The pet sheet test says where a pet's defense comes from (#396)

One test message corrected. A pet's combat-stats snapshot carries no defense pair, because `UnitDefense("pet")` computes the pet's level × 5 itself (`CGUnit_C` `0x613680`). The message added in #391 said benilla had no pet defense, which is wrong.

Verified: the `ui_pet_doll` tests pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/benilla-app/src/ui_pet_doll.rs

@@ -132,7 +132,7 @@ mod tests {
         assert_eq!(
             s.defense_skill,
             (0, 0),
-            "no pet defense here; the reference answers UnitLevel × 5 and 0 (`0x613680`)"
+            "a pet's snapshot has no defense pair; `UnitDefense(\"pet\")` answers level × 5 itself"
         );
     }