refactor: Refactor RPN to use Number interface uniformly for stack values

This commit refactors the internal/rpn package to use the Number interface
instead of the old Value struct for stack values. Key changes:

1. Updated Number interface to include IsBool() and Bool() methods for
   boolean value support

2. Modified Float and Rat types to support boolean mode with:
   - isBool and boolVal fields
   - Float64() returns 1 for true, 0 for false
   - String() returns 'true' or 'false' for boolean values

3. Updated Stack to use []Number instead of []Value

4. Updated all operations to use the Number interface methods directly
   - Add, Sub, Mul, Div, Pow, Mod now use Float64() for values

5. Updated tests to use NewNumber() with mode parameter instead of
   NewNumberValue(), and use Float64() instead of Number()

Benefits:
- Simplified code - no need for toNumber() and NewNumberValue() wrappers
- Better type safety - stack values are Number interface instances
- Boolean-to-number coercion works correctly in all operations

0 files changed, 0 insertions, 0 deletions