Annotate the kernel's creature parameters with the protocols (#104)

[mmacy]

Every public creature parameter in core/combat.py, core/spells.py, core/effects.py, and core/items.py now names what the function reads through it, in place of Any and object.

• A parameter whose reads are the id, name, alignment, hit points, conditions, and stat modifiers takes Creature: has_condition, apply_healing, incapacitated, alignments_differ, check_immunity, validate_attack, select_targets, and their kin.
• One that reads THAC0, armour class, or a saving throw takes Combatant: attack_roll, resolve_attack, saving_throw, damage_roll, deal_damage (its destructive-kill path rolls the victim's saves), destroy_equipment, participant_modifier, melee_modifier_for, and resolve_splash_attack.
• One that reads level, spell book, or memorized spells takes Caster: memorize_spells, validate_cast, cast_spell, cast_from_scroll, validate_turn_undead, turn_undead, and the rest of the casting surface.
• One whose unguarded reads need what a single concrete type has takes that type: MonsterInstance for validate_breath, resolve_breath, drain_monster_hd, resolve_energy_drain's attacker, and turn_undead's candidates; Character for sword_control_check, imported under TYPE_CHECKING.
• A sequence parameter takes a Sequence of the same choice, and a spell's targets takes Creature values or the location strings the module already documented for place-targeted spells.

The three protocols are unchanged. No function reads, unguarded, an attribute both concrete types have that the protocols lack, so nothing was added to osrlib.core.creature.

Runtime behaviour is identical. No branch, guard, or draw was added or moved. The only executable changes are imports, six typing.cast calls (three in deal_damage, three in resolve_energy_drain) where a runtime gate the type checker cannot see has already settled which concrete type is in hand, and _ScrollReader keeping the scroll's caster level in a slot rather than behind a read-only property, so the proxy satisfies Caster where it is passed as one and declares the members it forwards. The rule behind each cast is stated in the function's own docstring. Every Args entry that promised a Character or a MonsterInstance in prose now links the protocol and says which concrete types satisfy it, and the module prose that described the parameters as duck-typed names the protocols instead.

Three crawl-layer declarations are typed in the second commit, because each launders a creature through object on its way into a kernel function and pyright had nothing to check until the kernel said what it reads: battle.py's slow_attacks element type, and exploration.py's two spell target lists. _use_device's healing target is typed Any rather than Creature | None, since its value is resolved in one effect_spec.kind == "healing" block and used in a second block testing the same condition, which pyright cannot correlate; narrowing it properly means restructuring those blocks, which belongs to a crawl-scoped change rather than this one. Nothing else in the crawl layer changed.

Gate, run in this worktree at 3d40cc6 after merging origin/main: uv run pyright reports 0 errors, 0 warnings, 0 informations; uv run ruff format --check reports 160 files already formatted; uv run ruff check passes; uv run pytest reports 2935 passed, 146 skipped, 2 xpassed with no golden file touched; uv run mkdocs build --strict builds clean. uv run pytest --runxfail tests/test_creature_protocols.py passes all 7 tests. The two xpasses are this chunk's own markers, left in place for the lead to remove.

Closes #104

https://claude.ai/code/session_01NmCezTw8hKKujkaEZ3YGAs