Give CPUs distinct personalities built on different poker libraries

Each CPU now thinks with one of four engines, each backed by a different
published library (pinned versions):

- montecarlo (@pokertools/evaluator): the existing balanced Monte Carlo
  equity player, moved to server/bots/montecarlo.js.
- calculator (poker-calculations): the library's decideAction over the
  table state; push/fold below 12BB via its jam breakeven equity.
  Skipped automatically if the native addon cannot load.
- range (poker-utils): tight player; preflop by hand-strength percentile,
  postflop equity vs an estimated opponent range, bluffs only when
  alpha/bluffEV say they pay.
- madehand (pokersolver): loose, sticky player that only looks at the
  made hand and draws.

server/ai.js assigns a mix of engines per table (makeStyles), falls back
to the Monte Carlo engine on errors, and legalizes every decision.
The engine and its parameters stay server-side; players cannot tell
which library a CPU uses. Tests cover every engine and the no-leak rule.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -16,6 +16,9 @@
     "@pokertools/engine": "2.1.0",
     "@pokertools/evaluator": "2.1.0",
     "express": "^4.22.3",
+    "poker-calculations": "4.0.3",
+    "poker-utils": "14.0.1",
+    "pokersolver": "2.1.4",
     "socket.io": "^4.8.4"
   }
 }