[Bug] Start conversation before LLM initialized

[kennywu0616]

LLM return "2131886081"

[muxi1998]

Fix the issue in #101

[Solution]

• Identified that the number string represents the resource ID of the error message. Updated the retrieval method to use Context to get the actual string instead of the resource reference.
• Added a warning dialog to inform the user when initialization is not complete.

[Validation]

• Quickly enter text and tap the send button.
• A warning dialog should appear if initialization is not ready.