fix(hookify): match file rules against Write tool content

[clown6613]

What

A simple-pattern hookify rule with event: file (e.g. the README's "Warn About Debug Code" example, pattern: console\.log\() silently never fired when Claude created a new file via the Write tool.

Root cause

config_loader infers the field name new_text for event: file simple-pattern rules. In rule_engine._extract_field, the new_text/new_string branch only read tool_input['new_string'] (the Edit field):

elif field == 'new_text' or field == 'new_string':
    return tool_input.get('new_string', '')   # Write content is in 'content', not 'new_string'

The Write tool stores file content in tool_input['content'], so the branch returned '' and the pattern never matched. The adjacent content branch already does the right fallback.

Fix

elif field == 'new_text' or field == 'new_string':
    # Write uses 'content', Edit has 'new_string'
    return tool_input.get('new_string') or tool_input.get('content', '')

Verification

event: file, pattern: console\.log\(:

tool	before	after
Write (new file, content)	❌ no match	✅ match
Edit (new_string)	✅ match	✅ match

$ python3 -c "..."   # via RuleEngine._rule_matches
before: Write=False Edit=True
after:  Write=True  Edit=True