Update documentation to match current workflow-core API

Fix numerous documentation inaccuracies to align with the actual
workflow-engine-core dev-main API:

- api-reference.md: Add WorkflowAction interface (canExecute, getName,
  getDescription), fix WorkflowContext properties (stepId not
  currentStepId, add config/instance/executedAt), correct with() and
  withData() signatures, fix WorkflowState enum cases (PENDING not
  Pending), add WAITING state, add isActive/isFinished/isSuccessful/
  isError/description/getValidTransitions methods, fix ActionResult
  API (remove non-existent retry(), fix success/failure signatures,
  add metadata support, document all methods), fix SimpleWorkflow API,
  add QuickWorkflowBuilder, Events, and Exceptions sections

- getting-started.md: Fix Laravel version requirement (11.0+), correct
  workflow starting via engine, add all WorkflowAction interface
  methods to examples, fix WorkflowState labels and add new methods

- advanced-features.md: Remove non-existent fork/join, Async attribute,
  priority(), globalTimeout(), step() method, chained retry/timeout/
  onFailure methods. Replace with actual API (addStep with params,
  QuickWorkflowBuilder templates). Fix all code examples

- best-practices.md: Fix step() to addStep(), remove ActionResult::retry(),
  replace property access with method calls (isSuccess, getErrorMessage,
  getData), fix context property (stepId not currentStepId), correct
  WorkflowContext constructor

- migration.md: Fix WorkflowState enum cases, correct WorkflowContext
  constructor and with/withData signatures, remove non-existent chained
  methods, add ActionResult API migration section

https://claude.ai/code/session_0116MrcGBE7oBdTM7D5EtofN

Author: claude