fix(sql_database): map FLOAT/REAL/DOUBLE to double under SQLAlchemy 2.1

[Aryan-Pardeshi]

Fixes #4313

Problem

sqla_col_to_column_schema dispatches float columns via isinstance(sql_t, sqltypes.Numeric). In SQLAlchemy 2.1, Float (and REAL/DOUBLE) no longer subclass Numeric — both now derive from the new NumericCommon base — so FLOAT/REAL/DOUBLE columns fall through to the unknown-type warning branch and lose their data_type entirely.

Change

Add a dedicated isinstance(sql_t, sqltypes.Float) branch after the Numeric branch, mapping float types to data_type: "double" (the same value the Numeric branch produces for asdecimal=False). Version-safe: on SA < 2.1 the Numeric branch still matches first; on 2.1 the Float branch catches Float/REAL/Double.

Tests

• test_float_types_mapped_to_double (sa.Float, sa.REAL)
• test_double_mapped_to_double_sa2 (sa.Double, SA >= 2.0)
• test_numeric_mapped_to_decimal_not_shadowed (Numeric(10,2) still → decimal + precision/scale)

Verified: tests/sources/sql_database/test_schema_types.py — 21 passed under SQLAlchemy 2.0.51 and 2.1.0b3 (where issubclass(Float, Numeric) is False).