feat: add chatbot introduction to CLI welcome panel

Adds a short description of what the chatbot does: answers from
your documents only, cites every claim, uses 6-layer verification,
and refuses rather than guessing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app_cli.py

@@ -191,6 +191,13 @@ def main() -> None:
     welcome = Text()
     welcome.append(f"{bot_name}", style="bold cyan")
     welcome.append(f" -- Your {domain} research assistant\n\n", style="dim")
+    welcome.append(
+        "I answer questions using only the documents in your knowledge base. "
+        "Every claim is cited with numbered references, and a 6-layer "
+        "verification system checks each answer before showing it to you. "
+        "If I can't find the answer in your documents, I'll say so rather "
+        "than guess.\n\n",
+    )
     welcome.append("Type your question, or /help for commands.\n", style="italic")
     welcome.append("Type /quit to exit.", style="italic dim")
     console.print(Panel(welcome, title="Welcome", border_style="cyan"))