fix: preserve Goose result spacing and bump version

[LIU9293]

Summary

• preserve whitespace across Goose response chunks so result messages no longer collapse words (for example Hi! How can I help you today?)
• add a regression test that reproduces chunked assistant output with leading spaces and verifies final text formatting
• bump package version from 0.0.70 to 0.0.71

Testing

• bun test packages/agents/test/goose-client-parse.test.ts
• bun test packages/agents/test/goose-stream-status.test.ts