Formatting chatbot output code correctly

[bwhewe-13]

Improves JSON response handling in the chat/agent output pipeline:

• agents.py: clarify the retry prompt sent when a response fails JSON validation, explicitly instructing the model to preserve original content verbatim (including code blocks) rather than summarizing or truncating it while fixing JSON structure/escaping.
• json_parsing.py: make extract_json_block's brace-matching string-aware, so braces inside quoted strings (including escaped quotes) are no longer miscounted as JSON structure.
• basewf.md: add a workflow rule directing the agent to use the write_file action for file-creation requests instead of pasting full file contents into chat messages.