Improve support for reasoning models

[djfarrelly]

Changes and improvements include:

• Add ReasoningMessage type to support reasoning/thinking content from OpenAI (o-series, gpt-*-pro/codex) and Anthropic (extended thinking) models
• Extract reasoning_content from OpenAI responses and thinking blocks from Anthropic responses into the new message type
• Filter reasoning messages from outbound requests across all adapters (OpenAI, Anthropic, Gemini)
• Improve OpenAI reasoning model detection with isReasoningModel() helper, replacing hardcoded o1/o3 checks
• Fix potential infinite loop in agent run loop when model output contains only reasoning messages (no stop_reason)
• Stream reasoning content via reasoning.delta events when streaming is enabled

[linear]

EXE-1250 AgentKit fails to work with gpt-5.2 reasoning models

[changeset-bot]

🦋 Changeset detected

Latest commit: 2ff46bf

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@inngest/agent-kit	Patch

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