fix(openai): enforce strict tool schema for Kimi Coding API

[ffrappo]

Problem

The Kimi Coding endpoint (`https://api.kimi.com/coding/v1\`) validates tool JSON schemas strictly and rejects schemas that include nullable enum patterns (e.g. `null` inside `enum`) that Forge already normalizes for other providers via `EnforceStrictToolSchema`.

The `kimi_coding` provider was not included in that pipeline, so requests with tools could fail against the Kimi Coding API.

Change

Include the `kimi_coding` provider in the same strict-schema branch as Fireworks, OpenCode Zen/Go, and XAI.

Testing

• `cargo build -p forge_main --release` (local)

Made with Cursor

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