- ContentMacro: add __post_init__ to auto-derive raw_text when built
programmatically, preventing str.replace("", X) corruption
- MacroParser: add @{target} shorthand syntax support mapped to REQUIRED kind,
updating parse, has_macros, count_macros, and find_macro_positions
- Artifact: store content in model and SQLite DB, replace resolver placeholder
with actual artifact content, add migration for existing databases
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>