* fix: align datasource plugin environment
* refactor: inject managed Kimi env into all stdio plugins
Pin the datasource credential-name test to the canonical
resolveKimiCodeOAuthKey so a digest drift in the standalone plugin
fails CI, and drop the hardcoded plugin-name special case so every
stdio plugin receives the active managed Kimi base URL / OAuth host
consistently (process.env and KIMI_CODE_HOME are already shared with
all plugins).
