Initial commit: BMAD framework + Story 1.1 Component Trait Definition

Features:
- BMAD (Build Modular AI-driven Development) framework setup
- BMM, BMB, CIS, Core modules configured
- Story 1.1: Component trait with error handling
- Workspace Cargo.toml with components crate
- 31 tests passing (19 unit + 12 doc tests)

Technical:
- Component trait with compute_residuals, jacobian_entries, n_equations
- ComponentError enum with thiserror
- JacobianBuilder for sparse matrix construction
- Object-safe trait supporting Box<dyn Component>
- Comprehensive documentation and examples

_bmad/bmm/workflows/2-plan-workflows/create-prd/templates/prd-template.md

@@ -0,0 +1,10 @@
+---
+stepsCompleted: []
+inputDocuments: []
+workflowType: 'prd'
+---
+
+# Product Requirements Document - {{project_name}}
+
+**Author:** {{user_name}}
+**Date:** {{date}}