feat(AliasDataFrame): Phase 9a - ArrowComputeMapper foundation

Add PyArrow expression compilation layer for accelerated compute:
- AST-based expression parsing (mirrors convert_expr_to_root pattern)
- 38 function mappings (trig, hyperbolic, exp/log, rounding)
- Special handling: clip(), where(), log→ln mapping
- Integer division → float64 (matches Python 3 semantics)
- Expression caching for performance
- Graceful fallback with warnings for unsupported functions

Requires: PyArrow >= 14.0.0
Tests: 83 passed

Reviewed-by: GPT, Gemini, Claude (Architect)

Author: miranov25