feat: Add hookify plugin for custom hook rules via markdown

Adds the hookify plugin to public marketplace. Enables users to create custom
hooks using simple markdown configuration files instead of editing JSON.

Key features:
- Define rules with regex patterns to warn/block operations
- Create rules from explicit instructions or conversation analysis
- Pattern-based matching for bash commands, file edits, prompts, stop events
- Enable/disable rules dynamically without editing code
- Conversation analyzer agent finds problematic behaviors

Changes from internal version:
- Removed non-functional SessionStart hook (not registered in hooks.json)
- Removed all sessionstart documentation and examples
- Fixed restart documentation to consistently state "no restart needed"
- Changed license from "Internal Anthropic use only" to "MIT License"
- Kept test blocks in core modules (useful for developers)

Plugin provides:
- 4 commands: /hookify, /hookify:list, /hookify:configure, /hookify:help
- 1 agent: conversation-analyzer
- 1 skill: writing-rules
- 4 hook types: PreToolUse, PostToolUse, Stop, UserPromptSubmit
- 4 example rules ready to use

All features functional and suitable for public use.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

plugins/hookify/hooks/stop.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+"""Stop hook executor for hookify plugin.
+
+This script is called by Claude Code when agent wants to stop.
+It reads .claude/hookify.*.local.md files and evaluates stop rules.
+"""
+
+import os
+import sys
+import json
+
+# CRITICAL: Add plugin root to Python path for imports
+PLUGIN_ROOT = os.environ.get('CLAUDE_PLUGIN_ROOT')
+if PLUGIN_ROOT:
+    parent_dir = os.path.dirname(PLUGIN_ROOT)
+    if parent_dir not in sys.path:
+        sys.path.insert(0, parent_dir)
+    if PLUGIN_ROOT not in sys.path:
+        sys.path.insert(0, PLUGIN_ROOT)
+
+try:
+    from hookify.core.config_loader import load_rules
+    from hookify.core.rule_engine import RuleEngine
+except ImportError as e:
+    error_msg = {"systemMessage": f"Hookify import error: {e}"}
+    print(json.dumps(error_msg), file=sys.stdout)
+    sys.exit(0)
+
+
+def main():
+    """Main entry point for Stop hook."""
+    try:
+        # Read input from stdin
+        input_data = json.load(sys.stdin)
+
+        # Load stop rules
+        rules = load_rules(event='stop')
+
+        # Evaluate rules
+        engine = RuleEngine()
+        result = engine.evaluate_rules(rules, input_data)
+
+        # Always output JSON (even if empty)
+        print(json.dumps(result), file=sys.stdout)
+
+    except Exception as e:
+        # On any error, allow the operation
+        error_output = {
+            "systemMessage": f"Hookify error: {str(e)}"
+        }
+        print(json.dumps(error_output), file=sys.stdout)
+
+    finally:
+        # ALWAYS exit 0
+        sys.exit(0)
+
+
+if __name__ == '__main__':
+    main()