feat(schema): add streamUsage compatibility to turn off stream_options - #57255

Closes #57230 (the stream_options half; store was handled in #57239).

Chat Completions always sends stream_options: { include_usage: true }, and there was no way to turn it off from config. Strict OpenAI-style APIs that reject unknown fields (Sarashina in #57230, Databricks AI Gateway in #31156) fail with a 400.

Changes:

• Adds streamUsage to the public model/provider compatibility schema. "compatibility": { "streamUsage": false } on a provider or model drops stream_options from the request. Defaults to true, so behavior is unchanged unless set.
• Renames the internal supportsUsageInStreaming to streamUsage so config and the AI package share one name, and removes the always-true detector plus Cohere's redundant true.
• Regenerates the client types, packages/protocol/openapi.json, and the services/www OpenAPI docs. Only the two streamUsage hunks are included; the generator also produced unrelated drift already on dev, which is left out.

Example:

{
  "providers": {
    "example": {
      "package": "@opencode/ai/providers/openai-compatible",
      "settings": { "baseURL": "https://api.example.com/v1" },
      "compatibility": { "streamUsage": false }
    }
  }
}

Without usage chunks, token and cost numbers for that provider are only as good as what the API returns without include_usage.

Testing:

• bun test in packages/ai: all pass except the two Bedrock PDF cassettes, which fail only because of the host's AWS_REGION; they pass with it unset. New test: streamUsage: false omits stream_options.
• bun run typecheck in packages/ai and packages/schema; tsc for packages/core src and tests.
• packages/core config/provider, normalization, and model-resolver tests. New test: provider-level compatibility.streamUsage: false reaches the resolved runtime model.

Requested by: @rekram1-node (Aiden Cline via Slack)