Convert app/schemas.py → app/schemas/__init__.py so the contextual
module can live at app/schemas/contextual.py while keeping all existing
'from app.schemas import ...' calls unchanged.
ContextualScope mirrors the renderer's camelCase payload via
alias_generator=to_camel. render_scope_block produces a single-paragraph
human-readable summary injected into the contextual agent system prompt.
4 tests, all passing.
