Spruce up the startup banner

Signed-off-by: Brianna Major <brianna.major@kitware.com>

Author: bnmajor

src/vtk_prompt/vtk_prompt_ui.py

@@ -17,6 +17,7 @@
 """
 
 import sys
+import textwrap
 from typing import Any
 
 import vtk
@@ -261,11 +262,22 @@ def start(self) -> None:
         self.server.start()
 
 
+def _print_startup_banner() -> None:
+    """Print a styled startup banner with ANSI colors."""
+    banner = textwrap.dedent("""\
+        \033[36m╭──────────────────────────────────────────────────────────────────────╮
+        │  \033[1mVTK Prompt UI\033[0m\033[36m                                                       │
+        │  \033[97mEnter your API token in the application settings.\033[36m                   │
+        │  \033[97mSupported providers: OpenAI, Anthropic, Google Gemini, NVIDIA NIM\033[36m   │
+        │  \033[97mFor local Ollama, use custom base URL and model configuration.\033[36m      │
+        ╰──────────────────────────────────────────────────────────────────────╯\033[0m
+    """)
+    print(banner)
+
+
 def main() -> None:
     """Start the trame app."""
-    print("VTK Prompt UI - Enter your API token in the application settings.")
-    print("Supported providers: OpenAI, Anthropic, Google Gemini, NVIDIA NIM")
-    print("For local Ollama, use custom base URL and model configuration.")
+    _print_startup_banner()
 
     # Check for custom prompt file in CLI arguments
     custom_prompt_file = None