Update terminal configuration and enhance CLI model management

- Changed default Docker, Singularity, and Modal images in configuration files to use "nikolaik/python-nodejs:python3.11-nodejs20" for improved compatibility.
- Updated the default model in the configuration to "anthropic/claude-sonnet-4.5" and adjusted related setup prompts for API provider configuration.
- Introduced a new CLI option for selecting a custom OpenAI-compatible endpoint, enhancing flexibility in model provider setup.
- Enhanced the prompt choice functionality to support arrow key navigation for better user experience in CLI interactions.
- Updated documentation in relevant files to reflect these changes and improve user guidance.

cli-config.yaml.example

@@ -55,7 +55,7 @@ terminal:
 #   cwd: "/workspace"
 #   timeout: 180
 #   lifetime_seconds: 300
-#   docker_image: "python:3.11"
+#   docker_image: "nikolaik/python-nodejs:python3.11-nodejs20"
 
 # -----------------------------------------------------------------------------
 # OPTION 4: Singularity/Apptainer container
@@ -67,7 +67,7 @@ terminal:
 #   cwd: "/workspace"
 #   timeout: 180
 #   lifetime_seconds: 300
-#   singularity_image: "docker://python:3.11"
+#   singularity_image: "docker://nikolaik/python-nodejs:python3.11-nodejs20"
 
 # -----------------------------------------------------------------------------
 # OPTION 5: Modal cloud execution
@@ -79,7 +79,7 @@ terminal:
 #   cwd: "/workspace"
 #   timeout: 180
 #   lifetime_seconds: 300
-#   modal_image: "python:3.11"
+#   modal_image: "nikolaik/python-nodejs:python3.11-nodejs20"
 
 # -----------------------------------------------------------------------------
 # SUDO SUPPORT (works with ALL backends above)