* Update cel to 0.11.6

* Refactor logging and improve error handling in CEL execution

* Set version to 0.5.4

* fix(pyi): correct cel.evaluate call signature

The implementation changed in 54d0d68,
but the pyi definition was not updated accordingly.

* Remove import EvaluationMode

Add ability to compile CEL expressions once and execute them multiple times
with different contexts. This provides ~12x speedup over evaluate() when
reusing the same expression.

New API:
- compile(expression) -> Program
- Program.execute(context) -> result

Example:
    program = compile('x + y')
    program.execute({'x': 1, 'y': 2})  # 3
    program.execute({'x': 10, 'y': 20})  # 30

Add examples demonstrating compile() and Program.execute() usage to README, quick-start guide, and Python API reference. Show performance pattern of compiling once and executing multiple times with different contexts.