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>

tests/test_equity.py

@@ -0,0 +1,42 @@
+"""Deterministic equity/board-eval — the JJ-vs-65 hand Lyra kept botching."""
+from __future__ import annotations
+
+import pytest
+
+from lyra import equity
+
+
+def test_flop_equity_and_made_hands():
+    r = equity.analyze(["Jh", "Js"], ["6d", "5d"], ["8c", "7d", "Ts"])
+    assert r["ahead"] == "hero"
+    assert r["hero_hand"] == "Pair" and r["villain_hand"] == "High Card"
+    assert 75 < r["hero_equity"] < 82  # ~78.7%
+
+
+def test_turn_villain_straight_and_outs_exclude_flush_card():
+    r = equity.analyze(["Jh", "Js"], ["6d", "5d"], ["8c", "7d", "Ts", "4d"])
+    assert r["ahead"] == "villain"
+    assert r["villain_hand"] == "Straight"
+    # hero's only outs are the three non-diamond nines — 9d makes villain a flush
+    assert r["hero_outs"]["count"] == 3
+    assert "9d" not in r["hero_outs"]["cards"]
+    assert r["hero_equity"] < 10
+
+
+def test_rejects_unknown_and_duplicate_cards():
+    with pytest.raises(equity.EquityError):
+        equity.analyze(["x", "x"], ["6d", "5d"], ["8c", "7d", "Ts"])
+    with pytest.raises(equity.EquityError):
+        equity.analyze(["8c", "8c"], ["6d", "5d"], ["8c", "7d", "Ts"])
+
+
+def test_unknown_suits_spread_rainbow_no_phantom_flush():
+    # all-unknown-suit board must not become monotone (which would inflate equity)
+    r = equity.analyze(["Jx", "Jx"], ["6d", "5d"], ["8x", "7x", "Tx"])
+    assert 75 < r["hero_equity"] < 82
+
+
+def test_tool_dispatch():
+    from lyra import tools
+    out = tools.dispatch("analyze_spot", {"hero": "Jh Js", "villain": "6d 5d", "board": "8c 7d Ts 4d"})
+    assert "EQUITY" in out and "Straight" in out