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/level.go

@@ -10,13 +10,13 @@ type Place struct {
 // Level is the current dungeon level: the map and everything on it. It is
 // reset in place by NewLevel, matching the C reuse of the global arrays.
 type Level struct {
-	Places   [MaxLines * MaxCols]Place
-	Rooms    [MaxRooms]Room
-	Passages [MaxPass]Room // one pseudo-room per passage network
-	Objects  []*Object     // lvl_obj: objects on this level
-	Monsters []*Monster    // mlist: monsters on the level
-	Stairs   Coord         // location of the staircase
-	NTraps   int           // number of traps on this level
+	Places    [MaxLines * MaxCols]Place
+	Rooms     [MaxRooms]Room
+	Passages  [MaxPass]Room // one pseudo-room per passage network
+	Objects   []*Object     // lvl_obj: objects on this level
+	Monsters  []*Monster    // mlist: monsters on the level
+	Stairs    Coord         // location of the staircase
+	TrapCount int           // number of traps on this level
 }
 
 // At returns the map cell at (y, x); the C INDEX(y,x) macro, including its