fix(bot):Fix vlm config bug and change session default threshold

[yeshion23333]

Description

1. 修复bot使用vlm配置时LiteLLM风格的报错；
2. 调整bot session commit的默认token阈值为200K

Related Issue

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🏅 Score: 92

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 Multiple PR themes Sub-PR theme: Fix VLM config LiteLLM style bug Relevant files: bot/vikingbot/config/loader.py Sub-PR theme: Adjust session commit default token threshold to 200K Relevant files: bot/vikingbot/config/schema.py

⚡ No major issues detected

[github-actions]

PR Code Suggestions ✨

No code suggestions found for the PR.