Do not derive model context from prompt and output token limits

Describe the bug

The model details display can overstate total context if it derives context by adding max_prompt_tokens and max_output_tokens. These are independent maxima and their sum may exceed max_context_window_tokens.

Affected version

1.0.81

Steps to reproduce the behavior

1. Return synthetic model metadata with max_prompt_tokens: 100000, max_output_tokens: 20000, and max_context_window_tokens: 100000.
2. Open the CLI model details display.
3. Check whether it reports 120,000 tokens instead of the declared 100,000-token context window.

Expected behavior

Display max_context_window_tokens as the total context window. Treat prompt and output limits as independent maxima rather than values whose sum defines context.

Additional context

The Copilot SDK/runtime preserves the independent context value, so this appears limited to CLI presentation.

Beginne bei der Anzeige der Modelldetails in der CLI und verfolge, wie synthetische Modellmetadaten formatiert werden. Reproduziere dies mit max_prompt_tokens 100000, max_output_tokens 20000 und max_context_window_tokens 100000; abgeschlossen ist die Aufgabe, wenn die Anzeige das deklarierte Kontextfenster von 100000 Token meldet und dabei Prompt- und Ausgabelimits unabhängig hält.