Fix outdated response access syntax in Basic Prompt Structure notebooks

[iskysun96]

Summary

• Replace response[0].text with response.content[0].text in all three variants of 01_Basic_Prompt_Structure.ipynb
• The old response[0].text syntax no longer works with the current Anthropic Python SDK — the correct way to access response text is response.content[0].text
• Affects: Anthropic 1P, AmazonBedrock/anthropic, and AmazonBedrock/boto3 notebooks (4 cells each, 12 total)

Test plan

• Open each modified notebook and verify cells render correctly
• Run the intentionally-broken example cells (malformed messages) and confirm they still raise the expected API error
• Run the working example cells and confirm response.content[0].text returns Claude's response correctly

🤖 Generated with Claude Code