fix(fp-check): use correct JSON response format in stop hooks

[jonathanreedmevs]

Summary

• Stop and SubagentStop hook prompts were instructing Claude to return plain text ('block' or 'approve')
• Claude Code expects prompt-type hooks to respond with JSON, causing Stop hook error: JSON validation failed on every session end
• Updated both prompts to respond with {"decision": "block", "reason": "..."} to block, or {} to allow stopping

Root Cause

The hook prompts on line 10 and line 22 ended with:

return 'block' with the specific gaps.
return 'approve'.

Claude Code parses the hook response as JSON. Plain text fails JSON validation, producing the error even though the hook logic itself was correct.

Fix

Replace plain-text return instructions with explicit JSON response format matching the Claude Code stop hook schema (decision field). Bump version to 1.0.1 so installed clients receive the update.

- If ANY bug is missing ANY of these phases or the gate review, return 'block' with the specific gaps.
- If all bugs have complete verification with verdicts, return 'approve'.
- If the conversation is not about fp-check verification at all, return 'approve'.
+ If ANY bug is missing ANY of these phases or the gate review, respond with JSON: {"decision": "block", "reason": "<specific gaps>"}
+ If all bugs have complete verification with verdicts, respond with JSON: {}
+ If the conversation is not about fp-check verification at all, respond with JSON: {}

Same change applies to the SubagentStop prompt on line 22.

Discovery

Bug discovered by Claude while debugging the Stop hook error: JSON validation failed error during active use of the fp-check skill.

Bug Replication

• Start a Claude Code session with fp-check installed
• Prompt Claude with anything
• Confirm Stop hook error: JSON validation failed appears
• Apply fix, restart session, confirm error is gone

[claude]

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