fix: target player for AnyPlayer potions

[Julian-Moncarz]

Summary

Fix AnyPlayer potions so the headless CLI targets the player creature when constructing UsePotionAction.

Before this change, an AnyPlayer potion such as Liquid Bronze could be consumed without applying its player-targeted effect. In the regression test, Liquid Bronze disappears from the potion list but no Thorns power is added.

Changes

• Treat TargetType.AnyPlayer like other player-targeting potion types in DoUsePotion.
• Add stable id fields to serialized player potions and player/enemy powers, so tests and downstream agents do not need localized display names.
• Add a regression test using seed p3, selecting Phial Holster by its stable text_key.
• The test enters combat, uses LIQUID_BRONZE, and verifies the player gains THORNS_POWER.

Tests

Red before the fix:

pytest tests/test_potions.py -q
# failed: player_powers did not contain Thorns after Liquid Bronze was consumed

Green after the fix:

pytest tests/test_potions.py -q
# 1 passed

pytest -q -k 'not test_skip_card and not test_heal_caps_at_max'
# 56 passed, 2 deselected, 1 warning

dotnet build src/Sts2Headless/Sts2Headless.csproj -c Release
# Build succeeded

Note: tests/test_card_reward.py::TestCardReward::test_skip_card and tests/test_rest_site.py::TestRestSiteActions::test_heal_caps_at_max fail on clean upstream with my current game DLLs as well, so I excluded them from the broader validation run.