feat(state): CharacterSheet — store the inputs, derive the rest

Stores only what was rolled or chosen, plus current hp/mp (the only two numbers
that genuinely mutate). Everything else is a function, so no derived number can
drift from its inputs and M5's level curve is a function change, not a migration.

LCK has no row and no accessor here — §7 holds by construction.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QYa9u7Kdxv5gX4AnwWexy8

client/scripts/state/character_sheet.gd

@@ -0,0 +1,94 @@
+class_name CharacterSheet
+extends RefCounted
+## The character, as state (§2). STORES only what was rolled or chosen, plus the two
+## numbers that genuinely mutate in play (current hp/mp). Everything else is DERIVED —
+## so a derived number can never drift from the inputs that produced it, and M5's level
+## curve becomes a function change rather than a stored-field migration.
+##
+## LCK IS NOT HERE, and there is no accessor for it. It lives in GameState.luck: no
+## save, no skill, no row (§7). That holds by construction, not by discipline.
+
+const PROF_BONUS_L1 := 2
+
+# --- stored: rolled, chosen, or genuinely mutable -------------------------------
+var attributes: Dictionary = {}   # {str,dex,con,fth,mag} — final, post-spend
+var race_id: String = ""
+var calling_id: String = ""
+var level: int = 1
+var skills: Array = []            # chosen + race-granted + the human's bonus pick
+var bonus_skill: String = ""      # human only; also present in `skills`
+var hp: int = 0                   # CURRENT hp — combat writes this
+var mp: int = 0                   # CURRENT mp
+
+
+# --- derived: functions, never stored -------------------------------------------
+func modifier(stat: String) -> int:
+	return Attributes.modifier(int(attributes.get(stat, 10)))
+
+
+func prof_bonus() -> int:
+	return PROF_BONUS_L1  # the level curve is M5's; creation is L1
+
+
+func max_hp() -> int:
+	return Callings.hit_die(calling_id) + modifier("con")
+
+
+func max_mp() -> int:
+	# TUNABLE — M5 owns the real MP curve (races-and-classes spec §6 defers it).
+	# The SHAPE is what M4-b needs to draw a bar: martials have no pool at all; a
+	# caster's scales off the casting stat, with a floor so a bad roll still casts.
+	if not Callings.is_caster(calling_id):
+		return 0
+	return maxi(4, 4 + 4 * modifier(Callings.casting_stat(calling_id)))
+
+
+func ac() -> int:
+	return 10 + modifier("dex")  # armor is an item -> M7
+
+
+func initiative() -> int:
+	return modifier("dex")
+
+
+func is_proficient(skill: String) -> bool:
+	return skill in skills
+
+
+func save(stat: String) -> int:
+	var v := modifier(stat)
+	if stat in Callings.saves(calling_id):
+		v += prof_bonus()
+	v += Races.save_bonus(race_id)  # human's +1 to all five
+	return v
+
+
+func poison_save_bonus() -> int:
+	# Situational (vs poison + the affliction track) — deliberately NOT folded into
+	# save("con"), because a conditional inside a flat number is a sheet that lies.
+	return Races.poison_save_bonus(race_id)
+
+
+func skill_bonus(skill: String) -> int:
+	var v := modifier(Skills.attribute(skill))
+	if is_proficient(skill):
+		v += prof_bonus()
+	return v
+
+
+func spell_dc() -> int:
+	if not Callings.is_caster(calling_id):
+		return 0
+	return 8 + prof_bonus() + modifier(Callings.casting_stat(calling_id))
+
+
+func has_nightsight() -> bool:
+	return Races.flag(race_id, "nightsight")
+
+
+func has_claws() -> bool:
+	return Races.flag(race_id, "claws")
+
+
+func has_keen_scent() -> bool:
+	return Races.flag(race_id, "keen_scent")