chore: add streaming response testing to CI workflow

[iuiaoin]

The test script previously only tested non-streaming mode (stream=False).
Now both streaming and non-streaming responses are tested sequentially,
and both must pass for the sample to be considered successful.

Changes to test_hosted_sample.py:

• Add stream parameter to send_test_request() function
• Handle streaming responses by collecting chunks via iter_lines()
• Run non-streaming test first, then streaming test
• Report detailed status for each mode (passed/failed, chunk count)

Result JSON now includes:

• non_streaming: passed/failed
• streaming: passed/failed
• streaming_chunks: