This PR enhances the Stealth engine by enabling hot reloading of flow definitions, states, and reply files during development, allowing developers to update logic without restarting the Rails server.

Details:

Flows and States:

• In FlowManager#trigger_flow, flow files are reloaded on every request in development, or when a flow is not yet loaded.
• If a state is missing from the loaded flow, the flow file is reloaded once more in development to pick up recent changes.
• This allows seamless renaming or editing of flows and states with instant effect.

Replies:

• In ReplyManager#trigger_reply, reply files are always reloaded on every request in development.
• In other environments, reply files are loaded only if not already registered (cached).
• This removes the need to restart the server to see changes in replies.

Notes:

• Flow files are expected under stealth/flows/, and reply files under stealth/replies/.