fix: allow warm up with system prompt

[RemiliaForever]

No description provided.

[Copilot]

Pull Request Overview

This PR fixes warm-up functionality to allow warm-up requests that include a system prompt. The change ensures that models can be properly warmed up even when a system prompt is provided.

• Modified warm-up logic to accept requests with only a system prompt message
• Replaced default struct tags with a constructor function for better default value management
• Updated CLI to include system prompt in warm-up requests when specified

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
runner/server/handler/completion.go	Refactored default values from struct tags to constructor function and updated warm-up condition to allow system prompt
runner/cmd/nexa-cli/run.go	Added system prompt to warm-up request and included missing CLI flag for thinking mode

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[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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