Improve error recovery guidance in framework prompts

[bluesky050]

Summary

• fw.msg_misformat.md: Replace the generic "You have misformatted your message. Follow system prompt instructions…" with 6 specific JSON formatting rules. This directly tells the agent which rule it likely violated (missing tool_args, string booleans, extra text outside JSON, wrong tool name) instead of pointing it back to re-read the entire system prompt.

• fw.error.md: Add a 4-category error diagnosis checklist after the existing {{{error}}} payload. Without guidance, agents tend to retry the exact same action on error. The checklist prompts the agent to classify the error (parameter / environment / logic / timeout) and pick a category-appropriate recovery strategy, reducing stuck-in-retry loops.

Why these changes help

Both prompts are "second-chance" messages — the agent sees them only after something went wrong. The current prompts are minimally informative ("misformatted" / implicit "try again"), which gives the LLM little signal on what to change. Providing a short, structured checklist at the point of failure is cheaper and more reliable than hoping the agent re-derives the fix from the system prompt.

Test plan

• Send an intentionally malformed tool call (e.g. tool_args as a string instead of an object) and verify the agent corrects the format on the next attempt
• Trigger a tool error (e.g. call a non-existent tool name) and verify the agent classifies the error and switches approach rather than retrying identically
• Run a normal multi-step task and confirm no regression in tool call format or error recovery behavior