feat(runtime): allow tools to return raw MCP content directly

[tlgimenes]

What is this contribution about?

Tools created with createTool previously had their return values automatically wrapped into { structuredContent, content: [{ type: "text", text: JSON.stringify(result) }] }. This change allows tools to return raw MCP content directly (e.g., { content: [{ type: "image", ... }] }) by detecting when the result already has a valid MCP content array. This enables returning images, embedded resources, and other MCP content types without the forced JSON text wrapping.

How to Test

1. Create a tool that returns { content: [{ type: "text", text: "hello" }] } directly
2. Verify it passes through as-is without double-wrapping
3. Create a tool that returns a plain object like { foo: "bar" }
4. Verify it still gets auto-wrapped as before

Review Checklist

• PR title is clear and descriptive
• Changes are tested and working
• Documentation is updated (if needed)
• No breaking changes

---

Summary by cubic

Allow tools created with createTool to return raw MCP content directly, bypassing JSON wrapping when a valid array is provided. Also bumps @decocms/runtime to 1.5.0.

• New Features

  • Passes through results with a valid content array unchanged (including images and embedded resources).
  • Keeps auto-wrapping for plain objects into { structuredContent, content: [{ type: "text", text: JSON.stringify(result) }] }.

• Bug Fixes

  • Uses CallToolResult for passthrough to ensure correct typing.

^{Written for commit ae8bae9. Summary will update on new commits.}

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