[OMEGA-481] Fix: Plugin module identity

[timur-ashkenov]

Description

Fixes #360:

Plugins loaded by file location were not registered in sys.modules, so importing the same plugin elsewhere could create a separate module instance with its own state. This could cause components to use different queues or other shared objects.

This change registers location-loaded plugins in sys.modules, ensuring that subsequent imports reuse the same module and shared state. It also renames the OpenAI plugin to omega_openai to avoid naming conflicts with the OpenAI SDK.

How Has This Been Tested?

Verified shared module state, repeated loading, failure cleanup, name collisions, and Telegram queue sharing.

• tests/: 138 passed, 4 skipped.
• Autotests/unit/: 176 passed.

Checklist

• PR contains autogenerated code
• Self-review completed
• Test scenarios above are passed with the version of the code from PR

[MorozovMisha]

Tested: PR #389 f4cbc74

What I checked:

• Automated tests:
  • pytest -v tests/ -k "plugin": 22 passed of 22.
  • Verified test_import_returns_loaded_plugin[location], test_import_shares_initialized_state_and_outbox[location], and test_telegram_import_uses_registered_channels_outbox.
• Module registration:
  • Location-loaded plugins register in sys.modules[name] prior to execution.
  • Direct import <plugin> returns the exact module instance stored in _plugins[name].mod with shared globals and outbox state.
• Name collision protection:
  • If a module name is already occupied by another file or package on sys.path, _initPythonPlugin aborts with _error rather than silently replacing or shadowing the existing import.
• Shipped providers compatibility:
  • Built-in provider renamed to providers/omega_openai.py to prevent shadowing the external openai SDK.
• Documentation:
  • docs/reference-plugin-api.md updated with the module identity lifecycle rules, collision handling, and the omega_openai provider rename notes.

Verdict: PASS.

[timur-ashkenov]

@blackhammer116 Could you please re-approve it after merge with main?