Fix persistent history when used with teaser message

[kwinto]

Success criteria

Please describe what should be possible after this change. List all individual items on a separate line.

• When teaser message arrives, it still should restore the chat history.

How to test

Please describe the individual steps on how a peer can test your change.

1. Provide static session id.
2. Init with:

teaserMessage: {
    teaserMessageDelay: 5000,
    text: "Hi there!"
},

3. Do not wait for a teaser message to arrive and open the chat.
4. Talk to a bot.
5. Reload.
6. Again, do not wait to a teaser message, open the chat.
7. History should be restored.
8. Reload the page.
9. Wait for the teaser message. Click it.
10. History should be restored (previously it was not the case).

[Copilot]

Pull Request Overview

This PR fixes an issue where the chat history was not properly restored when using a teaser message.

• Adds a RESET_STATE action to conditionally restore persisted messages if the current message history is empty.
• Uses a specific condition to detect an "empty" history (or history with only an engagement message) to avoid duplicates.

[vj-venkatesan]

When there are multiple conversations (Through previous conversations) and I start a new conversation and follow your steps, the teaser always takes me to the oldest conversation

Say the following chat history

1. C (Recent)
2. B
3. A
   Clicking teaser always goes to A , is that we want ?

[kwinto]

When there are multiple conversations (Through previous conversations) and I start a new conversation and follow your steps, the teaser always takes me to the oldest conversation

Say the following chat history

1. C (Recent)
2. B
3. A
   Clicking teaser always goes to A , is that we want ?

If you have a distinct session id configured, it will always open that conversation.

[vj-venkatesan]

When there are multiple conversations (Through previous conversations) and I start a new conversation and follow your steps, the teaser always takes me to the oldest conversation
Say the following chat history

1. C (Recent)
2. B
3. A
   Clicking teaser always goes to A , is that we want ?

If you have a distinct session id configured, it will always open that conversation.

Ah yes that makes sense , what If i don't have a distinct session ?

[kwinto]

Ah yes that makes sense , what If i don't have a distinct session ?

It will then generate a random id for the session. So, the "Start conversation" button and the teaser message bubble would always lead to a new conversation.