feat: add TokenLab provider

[hedging8563]

Describe Your Changes

• Add TokenLab as a predefined remote provider using the OpenAI-compatible base URL https://api.tokenlab.sh/v1
• Add a curated default TokenLab model list covering GPT, Claude, Gemini, Grok, Qwen, DeepSeek, GLM, MiniMax and Kimi families
• Enable TokenLab remote model discovery via /models with conservative chat capability inference
• Add focused tests for default model selection, capability inference and catalog filtering

Fixes Issues

• Closes N/A

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed

Validation:

• git diff --check
• yarn test:web web-app/src/lib/__tests__/remoteModelCatalog.test.ts web-app/src/lib/__tests__/models.test.ts was attempted, but this temporary checkout has no installed Yarn/node_modules state file, so the command did not execute tests.