Add test suite and fix configuration for Python 3.12

- Add AGENTS.md with coding guidelines for AI agents
- Add comprehensive unit tests for Binance adapter (mocked)
- Add integration tests for Binance testnet connectivity
- Fix pydantic-settings v2 compatibility for nested settings
- Fix MarginType enum to handle lowercase API responses
- Update Python requirement to 3.12+ (pandas-ta dependency)
- Update ruff config to new lint section format
- Update PLAN.md to reflect completed milestones 1.1-1.3

32 tests passing with 81% coverage

tests/test_binance_integration.py

@@ -0,0 +1,80 @@
+import os
+from collections.abc import AsyncIterator
+from decimal import Decimal
+
+import pytest
+from dotenv import load_dotenv
+
+from tradefinder.adapters.binance_usdm import BinanceUSDMAdapter
+from tradefinder.core.config import (
+    Settings,
+    TradingMode,
+    get_settings,
+    reset_settings,
+)
+
+# Load .env file before checking for keys
+load_dotenv()
+
+BINANCE_TESTNET_KEYS = bool(
+    os.getenv("BINANCE_TESTNET_API_KEY") and os.getenv("BINANCE_TESTNET_SECRET")
+)
+
+pytestmark = pytest.mark.skipif(
+    not BINANCE_TESTNET_KEYS,
+    reason="BINANCE_TESTNET_API_KEY and BINANCE_TESTNET_SECRET are required",
+)
+
+
+@pytest.fixture(scope="session")
+def settings() -> Settings:
+    reset_settings()  # Clear any cached settings first
+    settings = get_settings()
+    if settings.trading_mode != TradingMode.TESTNET:
+        pytest.skip("Integration tests require testnet trading mode")
+    return settings
+
+
+@pytest.fixture
+async def adapter(settings: Settings) -> AsyncIterator[BinanceUSDMAdapter]:
+    adapter = BinanceUSDMAdapter(settings)
+    await adapter.connect()
+    try:
+        yield adapter
+    finally:
+        await adapter.disconnect()
+
+
+@pytest.mark.integration
+class TestBinanceIntegration:
+    async def test_connect_and_disconnect(self, settings: Settings) -> None:
+        adapter = BinanceUSDMAdapter(settings)
+        await adapter.connect()
+        assert adapter._client is not None
+        await adapter.disconnect()
+        assert adapter._client is None
+
+    async def test_get_usdt_balance(self, adapter: BinanceUSDMAdapter) -> None:
+        balance = await adapter.get_balance("USDT")
+        assert balance.asset == "USDT"
+        assert balance.wallet_balance >= Decimal("0")
+        assert balance.available_balance >= Decimal("0")
+
+    async def test_get_all_positions(self, adapter: BinanceUSDMAdapter) -> None:
+        positions = await adapter.get_positions()
+        assert isinstance(positions, list)
+        for position in positions:
+            assert position.symbol
+
+    async def test_get_symbol_info(self, adapter: BinanceUSDMAdapter) -> None:
+        symbol_info = await adapter.get_symbol_info("BTCUSDT")
+        assert symbol_info.symbol == "BTCUSDT"
+        assert symbol_info.tick_size > Decimal("0")
+
+    async def test_get_mark_price(self, adapter: BinanceUSDMAdapter) -> None:
+        mark_price = await adapter.get_mark_price("BTCUSDT")
+        assert mark_price > Decimal("0")
+
+    async def test_configure_hedge_mode(self, adapter: BinanceUSDMAdapter) -> None:
+        await adapter.configure_hedge_mode(True)
+        await adapter.configure_hedge_mode(False)