Add Docker init and runtime support for engine

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

Introduced the `AdditionalArguments` property in `DockerRunOptions` to allow specifying extra Docker command arguments.

Added the `GetDockerModeAsync` method to `IDockerService` and implemented it in `DockerService` to dynamically determine the Docker operating system type (Linux, Windows, or Unknown) using the `docker info` command.

Updated `RunContainerAsync` in `DockerService` to include `AdditionalArguments` in Docker commands.

Refactored `InitCommandOptionsHandler` to use `GetDockerModeAsync` for platform detection and set `AdditionalArguments` to `" --start"` when creating Docker containers.

Removed an extraneous closing brace in `InitCommand`.

These changes improve platform-awareness and enhance flexibility in Docker command execution.

#135