v0.1.1 - Provider credential forwarding fix

Fix Codex MCP environment forwarding for GLM, ZAI, DeepSeek, MoE4All, and documented compatible-provider credential variables.

• Declares supported environment variable names in the plugin MCP manifest
• Keeps credential values out of repository and provider configuration
• Adds a regression test for the forwarding contract
• Updates English and Chinese documentation
• 44 automated tests pass