Add test coverage checklist, report template, and stack matrix for ecommerce project

- Created a test coverage checklist to ensure comprehensive testing of backend and frontend components.
- Added a test report template to standardize reporting on test execution results and gaps.
- Introduced a test stack matrix to guide the selection of testing tools and frameworks for backend and frontend.
- Established a skill for repairing failing tests, including a failure triage checklist and a test repair template.
- Documented recommended MCP stack for ecommerce development with FastAPI and React/Next.js.
- Developed a detailed README outlining the project structure, agent capabilities, and recommended workflows.
- Compiled a comprehensive workflow guide detailing step-by-step commands for project setup, testing, and SEO implementation.

site-fullstack/.github/prompts/ecommerce-prepare-brief.prompt.md

@@ -0,0 +1,11 @@
+name: "Ecommerce Prepare Brief"
+description: "Turn a rough ecommerce request into .ai/STORE-BRIEF.md by asking focused questions and normalizing the project scope before code generation."
+agent: "shop-fullstack-fastapi-react"
+Prepare the project for implementation.
+
+Requirements for this run:
+- Do not start application scaffolding yet.
+- Ask only the minimum high-impact questions.
+- Create or update .ai/STORE-BRIEF.md.
+- Normalize the user request into a build-ready markdown brief for storefront, backend, admin panel, integrations, design, and AGENTS.md planning.
+- If the project is split across repos, make the current repo responsibilities explicit.