fix: unknown slash commands crash & incorrect handling

[deepak0x]

This PR fixes a bug where the app crashed if a user typed an unknown slash command (for example, /hello) and pressed Enter.

Now, unknown slash commands are treated as command attempts instead of normal chat messages. If the command does not exist on the server, the user will see a "No such command" message.

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Closes: #1144

Screenshots

Changes Made

1. packages/react/src/views/CommandList/CommandsList.js

• Added a safety check in handleKeyPress.
• Prevents the app from trying to access data when the command list is empty.
• This fixes the crash.

2. packages/react/src/hooks/useShowCommands.js

• Updated the logic so the command list is not shown when there are no matching commands.
• Keeps the UI clean and avoids unexpected behavior.

3. packages/react/src/views/ChatInput/ChatInput.js

handleCommandExecution

• Now tries to execute all slash commands using the API.
• Even if the command is not in the local list, it is sent to the server.
• If the server returns a 400 error (invalid command), a "No such command" toast is shown.

sendMessage

• Prevents slash commands from being sent as normal chat messages.
• Ensures they are handled only as commands.

[deepak0x]

hey @Spiral-Memory
Pls check this pr if you get time ;)
Thanks