feat: deterministic equity/board-reading tool (math via tools, not LLM)

Lyra was hallucinating poker facts — phantom flushes, missed straights, wrong
equity, only correcting when spoon-fed. Board reading + equity are combinatorial
facts an LLM can't do reliably; this is exactly the "math via deterministic
tools, never the LLM" principle.

- lyra/equity.py: treys-backed analyze(hero, villain, board) -> made hands,
  who's ahead, EXACT equity (enumerated), and outs (one to come). Handles 'Jx'
  unknown suits (assigned rainbow to avoid phantom flushes); rejects 'x'/dupes.
- analyze_spot tool wired into chat; persona MANDATES it for any equity/board/
  who's-ahead/outs question — never eyeballed.
- tests on the real JJ-vs-65 hand: flop 78.7%, turn villain straight + hero 6.8%
  with outs "9s 9h 9c" (correctly excludes 9d, which makes villain a flush).

Verified live: she now calls the tool and reports exact numbers, no hallucinated
flush.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -10,6 +10,7 @@ dependencies = [
     "numpy>=2.4.5",
     "openai>=2.37.0",
     "python-dotenv>=1.2.2",
+    "treys>=0.1.8",
     "uvicorn[standard]>=0.34",
 ]