refactor(context): rename ambient context helpers

[PakitoSec]

Summary

• rename the ambient context APIs from global_context_configure() to global_context() and from clear_context() to global_clear_context()
• update public exports, internal usages, examples, tests, and migration guidance to use the renamed helpers consistently
• bump the package version from 1.0.0b1 to 1.0.0b2

Testing

• update tests/test_core.py and tests/test_mp.py to cover the renamed public APIs
• refresh examples and docs so the published usage matches the new API names