Add Docker support for FlowSynx engine and resolve conflicts

This commit introduces Docker support for the FlowSynx engine,
including an implementation plan and necessary abstractions. Key
changes include:

- Added `IDockerService` abstraction for Docker operations.
- Introduced `flowctl init --docker` and `flowctl run --docker`
  commands for initializing and running the engine in Docker mode.
- Persisted deployment mode and Docker metadata in `appsettings.json`.
- Defaulted to a host bind mount (`~/.flowsynx/data -> /app/data`)
  for data persistence, with options for overrides.
- Addressed risks like Docker unavailability, port conflicts, and
  permission issues with clear error handling and guidance.

Additionally, resolved a merge conflict in `RunCommandOptionsHandler.cs`
between `feature/docker-engine` and `master` by integrating Docker
logic with upstream documentation and formatting improvements.
Tests were re-run to ensure correctness.

#134

Author: ziagham