feat(resolution): add automatic market resolution detector with conservative payout validation

- PolymarketClient.get_market_resolution(): query Gamma API by market id;
  resolved only when closed AND uma status final AND outcome prices binary
  (never settle on disputed/ambiguous outcomes)
- bot/main.py: check_resolutions() runs every 10 cycles (~10 min) in paper
  mode, settles open positions via PaperExecutor.close_position()
- close_reason now persisted as 'resolved' (resolution has its own column)
- tests/test_resolution_detector.py: 10 tests covering API parsing shapes
  and the BUY_NO settlement flow; 27/27 suite green

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_paper_close.py

@@ -95,7 +95,7 @@ def test_buy_no_loses():
 def test_position_is_removed_and_persisted():
     pnl, ex, db, notif = _close("BUY_YES", resolution=1.0)
     assert "mkt1" not in ex._portfolio.positions
-    assert db.closed == [("mkt1", "market_resolved resolution=1.0", 1.0)]
+    assert db.closed == [("mkt1", "resolved", 1.0)]
 
 
 def test_unknown_market_returns_none():