feat(infra): conexion y consulta directa a SQL Server (Navision) via pymssql

Grupo de capacidad nuevo 'sql-connect' (3 funciones) para conectar a un
Microsoft SQL Server (donde corre Navision) y consultar directamente, en
lugar del ida y vuelta manual de pegar CSVs.

- mssql_connect_py_infra: abre conexion pymssql (login_timeout acotado,
  credenciales por argumento, RuntimeError claro si falla).
- mssql_query_py_infra: SELECT parametrizada con binding seguro (sin
  inyeccion) sobre conexion abierta; devuelve {columns, rows, row_count};
  0 filas -> lista vacia; max_rows con fetchmany; read-only.
- run_mssql_query_py_pipelines: one-shot que compone connect+query y cierra
  siempre; CLI imprime JSON o CSV; contrasena desde env var (pass).

Pagina madre docs/capabilities/sql-connect.md + fila en INDEX.md.
Dependencia pymssql>=2.3.13 anadida a python/pyproject.toml + uv.lock.
Tests mock-based (11) verdes; error path verificado end-to-end contra el
driver real (host inalcanzable -> RuntimeError, acotado por login_timeout).

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

python/functions/infra/mssql_query_test.py

@@ -0,0 +1,133 @@
+"""Tests para mssql_query usando un doble de prueba (sin servidor real)."""
+
+from __future__ import annotations
+
+import os
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", ".."))
+
+from functions.infra.mssql_query import mssql_query
+
+
+def _desc(*names):
+    """Construye una description estilo DB-API: una tupla 7-elem por columna."""
+    return [(name, None, None, None, None, None, None) for name in names]
+
+
+class FakeCursor:
+    """Doble de prueba de un cursor DB-API (pymssql-like)."""
+
+    def __init__(self, description=None, rows=None):
+        self.description = description
+        self._rows = list(rows or [])
+        self.executed = None          # (sql, params) de la ultima execute
+        self.fetchmany_calls = []     # tamaños pedidos a fetchmany
+        self.closed = False
+
+    def execute(self, sql, params=None):
+        self.executed = (sql, params)
+
+    def fetchall(self):
+        return list(self._rows)
+
+    def fetchmany(self, size):
+        self.fetchmany_calls.append(size)
+        return list(self._rows[:size])
+
+    def close(self):
+        self.closed = True
+
+
+class FakeConn:
+    """Doble de prueba de una conexion: devuelve un FakeCursor fijo."""
+
+    def __init__(self, cursor):
+        self._cursor = cursor
+
+    def cursor(self):
+        return self._cursor
+
+
+def test_golden_maps_rows_to_dicts():
+    cur = FakeCursor(
+        description=_desc("No_", "Amount"),
+        rows=[("CLI-1", 100), ("CLI-2", 200)],
+    )
+    conn = FakeConn(cur)
+
+    result = mssql_query(conn, "SELECT No_, Amount FROM Cartera")
+
+    assert result == {
+        "columns": ["No_", "Amount"],
+        "rows": [
+            {"No_": "CLI-1", "Amount": 100},
+            {"No_": "CLI-2", "Amount": 200},
+        ],
+        "row_count": 2,
+    }
+    assert cur.closed is True
+
+
+def test_binding_passes_params_to_driver():
+    cur = FakeCursor(description=_desc("No_"), rows=[("CLI-0001",)])
+    conn = FakeConn(cur)
+    sql = "SELECT No_ FROM Cartera WHERE [Customer No_] = %s"
+
+    mssql_query(conn, sql, params=("CLI-0001",))
+
+    # El SQL y los params llegan al driver tal cual: binding, no interpolacion.
+    assert cur.executed == (sql, ("CLI-0001",))
+
+
+def test_zero_rows_no_error():
+    cur = FakeCursor(description=_desc("No_", "Amount"), rows=[])
+    conn = FakeConn(cur)
+
+    result = mssql_query(conn, "SELECT No_, Amount FROM Cartera WHERE 1 = 0")
+
+    assert result["rows"] == []
+    assert result["row_count"] == 0
+    assert result["columns"] == ["No_", "Amount"]
+
+
+def test_max_rows_uses_fetchmany():
+    cur = FakeCursor(
+        description=_desc("No_"),
+        rows=[("CLI-1",), ("CLI-2",), ("CLI-3",)],
+    )
+    conn = FakeConn(cur)
+
+    result = mssql_query(conn, "SELECT No_ FROM Cartera", max_rows=1)
+
+    assert cur.fetchmany_calls == [1]
+    assert result["row_count"] == 1
+    assert result["rows"] == [{"No_": "CLI-1"}]
+
+
+def test_description_none_empty_columns():
+    cur = FakeCursor(description=None, rows=[])
+    conn = FakeConn(cur)
+
+    result = mssql_query(conn, "SET NOCOUNT ON")
+
+    assert result["columns"] == []
+    assert result["rows"] == []
+    assert result["row_count"] == 0
+
+
+def test_execution_error_raises_runtimeerror():
+    class BoomCursor(FakeCursor):
+        def execute(self, sql, params=None):
+            raise ValueError("boom")
+
+    cur = BoomCursor()
+    conn = FakeConn(cur)
+
+    with pytest.raises(RuntimeError, match="mssql_query failed executing query"):
+        mssql_query(conn, "SELECT 1")
+
+    # El cursor se cierra incluso en error (try/finally).
+    assert cur.closed is True