Persistent memory for eve agents

eve agents can now retain context across sessions and use it in future conversations. Persistent memory is organized into slots. You can define named slots in files under agent/memory/ . Each slot specifies a provider, which stores and retrieves the memory, and a scope, which determines who or what shares it. For example, you can keep separate memory for each authenticated user. Before each turn, eve retrieves relevant memory and adds it to the model's context. Depending on the provider, memory can be updated automatically after a turn, through tools the agent uses, or through both methods. To