Fix logs package refactor: restore compatibility and forward Loguru into stdlib logging

[aidankhogg]

Motivation

• A recent refactor renamed the internal logging package causing unresolved logs imports and breaking tooling that expects a logging-style API.
• Tests and infrastructure tools (notably pytest caplog) stop observing warnings because records no longer flow into Python's standard logging system.

Description

• Rewired all internal imports to use the package netengine.logs instead of unresolved top-level logs and updated FastAPI middleware import in netengine/api/app.py.
• Added compatibility aliases in netengine/logs/__init__.py (getLogger, Logger alias, and standard level constants DEBUG/INFO/WARNING/ERROR/CRITICAL) so existing callers and tests using a logging-like API continue to work.
• Implemented a Loguru→stdlib bridge in netengine/logs/core.py that forwards Loguru records into Python's logging via an added add_stdlib_sink sink so integrations (e.g., pytest caplog) and other stdlib consumers capture emitted warnings/errors.
• Updated project references (README and pyproject.toml mypy excludes) to the new netengine/logs layout and adjusted test fixtures to import netengine.logs.

Testing

• Ran pytest tests/test_spec_parsing.py tests/test_pgmq_emitters.py -q and the focused suite passed (28 tests passed).
• Ran python -m compileall -q netengine tests/conftest.py tests/test_spec_parsing.py tests/test_pgmq_emitters.py which succeeded.
• Attempted a full test run with pytest -q but collection was blocked by a pre-existing IndentationError in tests/test_doctor.py, which is unrelated to the logging changes and prevented completing the entire suite.

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Codex Task