refactor(math): redesign math engine with pipeline architecture by antonreshetov · Pull Request #714 · massCodeIO/massCode

- analysisNormalize → classify → early return → rewrite → evaluate → format
- Speculative handlers for timezone, calendar, CSS, date arithmetic
- Modifier early path (rounding, strip-unit, format) before speculative checks
- useMathEngine.ts reduced from 1127 to ~480 lines