Audit Finding (Architecture, Medium)

Location: crates/agnix-core/src/pipeline.rs:355-585

run_project_level_checks (~230 lines) performs cross-file analysis for AGM-006, XP-004/005/006, VER-001. This belongs in a dedicated module, not in the orchestration layer.

Fix: Extract to rules/project_level.rs. Consider a ProjectAnalyzer trait for multi-file analysis. Move validation logic from schemas::cross_platform into rules::cross_platform, keeping only schema definitions in schemas/.

Found by /audit-project