refactor: remove legacy queue APIs

[cmilesio]

What

Remove the retired public bus and queuefake packages, workflow-observer aliases, root Config.Observer, and Redis ServerLogger. Root queue is now the sole application facade for dispatch, workflows, observation, and fakes.

flowchart LR
    App[Application] --> Q[queue.Queue]
    Q --> W[internal/workflow]
    Q --> D[driver runtime]
    D --> B[backend]

Loading

Removed surface	Canonical replacement
bus.*	root queue.*
queuefake.New()	queue.NewFake()
Config.Observer	queue.WithObserver(...)
WorkflowObserver and related aliases	queue.Observer and queue.Event
Redis ServerLogger	DriverBaseConfig.Logger

Replace facade-only integration coverage with a public root-queue chain and batch contract exercised across sync, workerpool, Redis, NATS, SQS, RabbitMQ, SQLite, MySQL, and Postgres. Regenerate the README API/examples and executed test-count evidence.

Why

The compatibility facade preserved duplicate public models for queueing, workflows, observation, and fakes. Removing it leaves one coherent API while retaining the internal delivery and orchestration separation needed for backend-specific behavior. The migration guidance and generated documentation now describe only supported APIs.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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