Nearby connections and multi app scenario

[MrCsabaToth]

feat: Add multi-app communication using Nearby Connections
This commit adds the ability for multiple app instances to communicate with each other using the Android Nearby Connection API.
The key features are:

• A new NearbyConnectionsManager class to handle the Nearby Connections API.
• Integration of the NearbyConnectionsManager with the LlmChatViewModel.
• A new UI for selecting the role of the app (commander or subordinate).
• A new UI for the nearby chat, including a checkbox for sending common messages.
• The ability to display the author of the message.

feat: Add commander failover logic
This commit adds the logic to handle the commander disconnection scenario.
If the commander disconnects, the subordinates will wait for a short grace period and then elect a new commander. This improves the robustness of the multi-app communication.

feat: Add commander reclaim logic
This commit adds the logic for the original commander to reclaim its role if it comes back online.
If the original commander comes back online, the subordinates will reconnect to it, and the temporary commander will become a subordinate again. This further improves the robustness of the multi-app communication.

feat: Add system prompts and local database
This commit adds the following features:

• A role selector on the role selection screen to allow you to choose between being the commander or an agent (1-5).
• System prompts for the commander and the agents.
• A local database using ObjectBox to store the system prompts.
• Integration of the system prompts with the LlmChatViewModel.

feat: Add message signing and verification
This commit adds the following features:

• A CryptoManager class to handle key generation, signing, and verification.
• Integration of the CryptoManager with the NearbyConnectionsManager.
• Message signing and verification for all messages sent over the nearby communication API.
• A warning message is displayed in the chat window if the signature of a message is invalid.

feat: Add identity verification
This commit adds the logic to verify that the claimed role in the message matches the cryptographic key used for signing the message.
If the identity of the sender does not match the signature, the message will be discarded, and a warning message will be displayed in the chat window.

feat: Add impersonation detection
This commit adds the following features:

• A mechanism to detect when two participants claim to be the same agent or the commander at the same time.
• A warning message is displayed in the chat window when an impersonation is detected.
• The system prompts are updated to include information about the possibility of impersonation and how to handle it.

feat: Add mission descriptions and vector database
This commit adds the following features:

• Mission descriptions for each agent in markdown format.
• The mission description is displayed when an agent is selected.
• A vector database using ObjectBox to store the mission descriptions.
• The mission descriptions are chunked and indexed into the vector database.

feat: Unify chat experience and improve communication protocol
This commit adds the following features:

• A single chat room screen for all chat functionality.
• A recipient field to each message to specify who the message is for.
• The local model is only fed messages that are meant for everyone or for me.