feat(ai): add send message raven ai function

[prathameshkurunkar7]

Add "Send Message" AI Function for Agent Communication

Overview

Introduces a new Send Message AI function that allows bots to send messages to users and channels mentioned in conversations.

Key Features

• Message Targeting: Parses @username and #channel mentions from messages
• Multi-format Support: Handles text content, file attachments, and document links
• Auto-channel Creation: Creates DM channels for user mentions automatically
• Validation: Ensures either content or file is provided

Technical Changes

• Added send_message() function with mention parsing logic
• Added extract_channel_mentions() method to RavenMessage class
• Added current_message_id parameter passing in AI handler to let the bot know the current message which would contain the mentions.

Impact

• Enables proactive bot communication workflows. In future we can use this function to handover tasks between agents.
• Allows bots to notify relevant users about document updates, alerts, etc.
• Supports multi-modal messaging (text, files, document links)

Video and Screenshots:

Expenso sends created expense claim to other user via mention(An example of us being able to send DocTypeLinks) -

https://github.com/user-attachments/assets/bbc525f7-4946-469d-9485-97bbb4d4d4a7

Report Wizard sends insights and charts generated to user and channel mentions -

[mzndako]

This looks great.. Does this logic account for messages where the agent is explicitly mentioned (@agent_name) in channels?