feat: add help response for unrecognized slash commands

[devin-ai-integration]

Add help response for unrecognized slash commands

Task Description

Modify the slash command dispatch workflow to handle unrecognized slash commands and provide helpful feedback to users.

Changes Made

1. Added outputs to slashCommandDispatch job to expose command and error-message status
2. Added new unrecognizedSlashCommand job that runs after slashCommandDispatch
3. Implemented different help text formatting:
   • For /help: Shows available commands with descriptions
   • For unrecognized commands: Shows error message + available commands

Testing

Note: This change will need to be tested after merging to main, as slash commands can only be tested on the main branch.

The workflow will respond to:

• /help with a list of available commands
• Any unrecognized slash command with an error message + available commands
• Regular slash commands will work as before

Link to Devin run: https://app.devin.ai/sessions/19bfcd3c77084c55b445d7ba46e5f65c

[devin-ai-integration]

Original prompt:

@Devin - In the CDK repo, can you modify our slash command dispatch workflow as follows: If someone enters a one-line comment that starts with `/`, let's assume they are trying to enter a slash command. If it doesn't match a supported command (including if they literally type `/help` - then post back a comment to them telling what slash commands are available.

[devin-ai-integration]

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