Fix SQLAlchemy true division semantics

[laughingman7743]

WHAT

• Compile integer true division with a floating-point divisor.
• Explicitly cast numeric and floating-point operands so Athena preserves SQLAlchemy true division semantics.
• Re-enable the complete SQLAlchemy TrueDivTest compliance class.
• Add compiler regression coverage for literal, bound, mixed numeric, and floating-point expressions.

Refs #736

WHY

Athena follows Trino integer and decimal coercion rules. The default SQLAlchemy compilation produced rounded integer results, a float instead of Decimal for numeric literals, and a REAL precision artifact for floating-point literals. Explicit type coercion makes all SQLAlchemy true division compliance cases return the expected values and Python types.

VALIDATION

• just lint
• .venv/bin/pytest tests/pyathena/sqlalchemy/test_compiler.py::TestAthenaStatementCompiler::test_visit_truediv_binary -n 1 -q (5 passed)
• .venv/bin/pytest tests/sqlalchemy/test_suite.py::TrueDivTest -n 1 -q (9 passed)

SELF-REVIEW

1. Correctness and regression: verified integer, decimal, mixed numeric/integer, and floating-point compilation; confirmed floor division remains unchanged; added literal-column and bound-parameter coverage.
2. Maintainability and compatibility: reused SQLAlchemy type constructs and the existing cross-version double-type helper; confirmed no public API or DBAPI conversion changes.