fix: wrap array tool results in object for Kiro API compatibility

[kipkaev55]

Summary

When a tool result content is a JSON array (e.g. [{"a":1},{"b":2}]), the proxy passes it as { json: [array] }. The Kiro API requires json to always be an object, not an array, and returns ValidationException: Improperly formed request.

Fix

// Before
content: [{ json: typeof msg.content === "string" ? tryParseJson(msg.content) : msg.content }]
// After
var _tr = typeof msg.content === "string" ? tryParseJson(msg.content) : msg.content;
if (Array.isArray(_tr)) _tr = { result: _tr };
content: [{ json: _tr }]

This commonly triggers with tools that return JSON arrays as content (e.g. todowrite).

Testing

tool result content: '[{"a":1},{"b":2}]' → Before: 400 → After: 200
tool result content: 'plain text' → Before: 200 → After: 200 (unchanged)
tool result content: '{"key":"value"}' → Before: 200 → After: 200 (unchanged)