Fix invalid `--model` argument

[leogdion]

⚠️ Potential issue | 🔴 Critical

Fix invalid --model argument

The CLI expects a full model identifier (e.g. claude-3.5-sonnet), not the shorthand sonnet. As written, the action will exit with “unknown model” and the workflow will fail. Please switch to a valid model slug.

-          claude_args: '--model sonnet --allowed-tools "Bash(gh issue view:*),Bash(gh search:*),Bash(gh issue list:*),Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*),Bash(gh pr list:*)"'
+          claude_args: '--model claude-3.5-sonnet --allowed-tools "Bash(gh issue view:*),Bash(gh search:*),Bash(gh issue list:*),Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*),Bash(gh pr list:*)"'

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          claude_args: '--model claude-3.5-sonnet --allowed-tools "Bash(gh issue view:*),Bash(gh search:*),Bash(gh issue list:*),Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*),Bash(gh pr list:*)"'

Originally posted by @coderabbitai[bot] in #105 (comment)