fix: make reasoning.exclude option actually suppress reasoning tokens

[hiSandog]

Summary

The reasoning.exclude option in providerOptions for OpenRouter/Codebuff providers was completely non-functional. Setting providerOptions.openrouter.reasoning.exclude = true would not suppress reasoning tokens from the stream.

Root Cause

In sdk/src/impl/llm.ts, the continue statement was inside an inner for loop over providers, so it only skipped to the next provider iteration — the yield on the following line was unconditionally reached regardless.

Fix

Replaced the inner for loop with .some() so the exclude flag correctly controls whether reasoning chunks are yielded:

const reasoningExcluded = (['openrouter', 'codebuff'] as const).some(
  (p) =>
    (params.providerOptions?.[p] as OpenRouterProviderOptions | undefined)
      ?.reasoning?.exclude,
)
if (!reasoningExcluded) {
  yield { type: 'reasoning', text: chunkValue.text }
}

Validation

• Logic verified manually — change is purely structural, no semantic difference in the check itself
• Type signature unchanged — OpenRouterProviderOptions type still used identically