fix:unify noagent set in construct and inference

[siyuan-youtu]

No description provided.

[Copilot]

Pull Request Overview

This PR unifies the validation logic for mode configuration by ensuring both construction and triggers modes use the same valid_modes validation set. It also adds helpful comments about the noagent option for performance optimization.

• Updated construction mode validation to use the centralized valid_modes list instead of hardcoded values
• Added clarifying comments about the noagent mode option for performance improvement

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
config/config_loader.py	Updated construction mode validation to use consistent valid_modes list
config/base_config.yaml	Added comments explaining the noagent performance option

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