Introduces a module-driven context provider system that allows modules to
dynamically contribute template context variables without hardcoding imports.
Key changes:
- Add context_providers field to ModuleDefinition in app/modules/base.py
- Create unified get_context_for_frontend() that queries enabled modules only
- Add context providers to CMS module (PLATFORM, STOREFRONT)
- Add context providers to billing module (PLATFORM)
- Fix SQLAlchemy cross-module relationship resolution (Order, AdminMenuConfig,
MarketplaceImportJob) by ensuring models are imported before referencing
- Document the entire system in docs/architecture/module-system.md
Benefits:
- Zero coupling: adding/removing modules requires no route handler changes
- Lazy loading: module code only imported when that module is enabled
- Per-platform customization: each platform loads only what it needs
- Graceful degradation: one failing module doesn't break entire page
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>