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/.claude-plugin/plugin.json

@@ -0,0 +1,9 @@
+{
+  "name": "hookify",
+  "version": "0.1.0",
+  "description": "Easily create hooks to prevent unwanted behaviors by analyzing conversation patterns",
+  "author": {
+    "name": "Daisy Hollman",
+    "email": "daisy@anthropic.com"
+  }
+}