Rename constants to descriptive names (refactor step 1)

Pure rename, no behavior change; the full suite (RNG goldens,
generation invariants, scripted sessions, save round trip) is
unchanged and green.

- Creature flags: IsHuh→Confused, IsHalu→Hallucinating,
  CanHuh→CanConfuse, CanSee→CanSeeInvisible, IsRun→Awake,
  SeeMonst→SenseMonsters, IsCanc→Cancelled, IsLevit→Levitating,
  IsBlind/IsGreed/IsHaste/IsTarget/IsHeld/IsInvis/IsMean/IsRegen/
  IsFly/IsSlow → Blind/Greedy/Hasted/Targeted/Held/Invisible/Mean/
  Regenerates/Flying/Slowed, IsFound→Found
- Object flags: IsCursed→Cursed, IsKnow→Known, IsMissl→Missile,
  IsMany→Stackable, ObjIsFound→WasFound, IsProt→Protected
- Room flags: IsDark/IsGone/IsMaze → Dark/Gone/Maze; place flags:
  FPass→FPassage, FPNum→FPassNum, FTMask→FTrapMask
- Trap types: TDoor→TrapDoor ... TMyst→TrapMystery
- Item subtypes: P*→Potion* (PLSD→PotionLSD, PMFind→
  PotionDetectMonsters, ...), S*→Scroll* (SIDRorS→
  ScrollIdentifyRingOrStick, ...), R*→Ring* (RAddHit→RingDexterity,
  RNop→RingAdornment, ...), Ws*→Wand* (WsElect→WandLightning, ...),
  weapons (TwoSword→WeaponTwoHandedSword, Shiraken→WeaponShuriken,
  ...), armor (RingMail→ArmorRingMail, ...)
- Counts: Max{Potions,Scrolls,Rings,Sticks,Weapons,Armors} →
  Num{Potion,Scroll,Ring,Wand,Weapon,Armor}Types; NTraps→NumTrapTypes
- Level.NTraps field → TrapCount (also in the save snapshot)
- Original C constant names preserved as comment breadcrumbs in
  types.go so the lineage stays greppable

TODO.md: step 1 moved to Completed, step 2 (typed kinds) promoted to
Next Step.

game/save.go

@@ -74,14 +74,14 @@ type SaveState struct {
 	HasAmulet  bool
 	SeenStairs bool
 
-	Places   []savedPlace
-	Rooms    [MaxRooms]Room
-	Passages [MaxPass]Room
-	Objects  []Object
-	Monsters []savedCreature
-	Dests    []destRef // parallel to Monsters
-	Stairs   Coord
-	NTraps   int
+	Places    []savedPlace
+	Rooms     [MaxRooms]Room
+	Passages  [MaxPass]Room
+	Objects   []Object
+	Monsters  []savedCreature
+	Dests     []destRef // parallel to Monsters
+	Stairs    Coord
+	TrapCount int
 
 	After     bool
 	Again     bool
@@ -179,7 +179,7 @@ func (g *RogueGame) snapshot() *SaveState {
 		Rooms:      g.Level.Rooms,
 		Passages:   g.Level.Passages,
 		Stairs:     g.Level.Stairs,
-		NTraps:     g.Level.NTraps,
+		TrapCount:  g.Level.TrapCount,
 		After:      g.After,
 		Again:      g.Again,
 		NoScoreF:   g.NoScore,
@@ -308,7 +308,7 @@ func (g *RogueGame) applySnapshot(st *SaveState) {
 	g.Level.Rooms = st.Rooms
 	g.Level.Passages = st.Passages
 	g.Level.Stairs = st.Stairs
-	g.Level.NTraps = st.NTraps
+	g.Level.TrapCount = st.TrapCount
 	g.After = st.After
 	g.Again = st.Again
 	g.NoScore = st.NoScoreF