Automatic inference of correct Computer-use Flag

[philipph-askui]

Anthropic added a new computer use beta flag for claude 4.5 opus: https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool

Hence, there is now 2 different beta flag configurations:

• "computer-use-2025-01-24" for Claude 4.5 Haiku and Sonnet
• "computer-use-2025-11-24" for Claude 4.5 Opus

There is exactly one correct flag per model and using a wrong (or no) flag will result in an error. Hence, we should automatically add the correct computer-use flag.

In this PR I added:

• an automatic assignment of the correct computer use flag in the act command
• the computer_use_20251124 flag for claude 4.5 opus (caution: we do not yet have the new computeruse tool implemented)