refactor: remove unused specs, exceptions, and request_id

The pyvyos.specs Pydantic models were never imported by the runtime and
had 0% test coverage. The pyvyos.exceptions hierarchy was defined but
never raised anywhere. The request_id helper generated UUIDs that were
attached to log records but never propagated to callers — half-implemented
tracing is worse than none.

This commit does not alter request/response logic or HTTP payloads. It
only removes code that was never executed and tests for that code.

Removed:
- pyvyos/specs/ (Pydantic models package)
- pyvyos/exceptions.py (SDKError, HttpError, ApiError, ValidationError)
- pyvyos/utils/ids.py (request_id helper)
- tests/test_exceptions.py
- tests/utils/test_ids.py

Edited:
- pyvyos/core/rest_client.py: drop request_id import and log extras
- pyvyos/utils/__init__.py: drop request_id export

Tests: 66 -> 57 passing. Coverage: 54% -> 87%.
Public API unchanged.

0 files changed, 0 insertions, 0 deletions