* feat: add Qwen International and US provider catalogs
* refactor: merge qwen-us into qwen-intl with regions support
* refactor: merge regional providers into single files with regions
Merge qwen-intl.toml into qwen.toml with [provider.regions] for
intl (Singapore) and us (Virginia) endpoints.
Merge minimax-cn.toml into minimax.toml with [provider.regions.china]
including separate api_key_env for China endpoint.
Uses new RegionConfig table format instead of simple string URLs.
Community-maintained TOML catalog for LibreFang. New models can be added
via PR without requiring a LibreFang binary release.
Includes validation script, bilingual docs, and GitHub templates.
Evan