New textarea in Content settings lets admins provide custom instructions
appended to the writer's system prompt. Steers style, structure, voice,
and formatting without editing code.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
All 14 test files updated to use correct constructor patterns (array-based
value objects, dependency injection for ContentAnalyzer, etc.) and verified
method names against source.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>