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/skills/ecommerce-build-from-brief/SKILL.md

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+---
+name: ecommerce-build-from-brief
+description: 'Build a full ecommerce project from .ai/STORE-BRIEF.md. Use for generating the FastAPI backend, React or Next.js frontend, admin panel, AGENTS.md, and delivery plan from a normalized brief file.'
+argument-hint: 'Optionally mention which parts to build first if .ai/STORE-BRIEF.md already exists'
+---
+# Ecommerce Build From Brief
+
+## When to use
+- Building a new ecommerce project after requirements have been normalized.
+- Continuing implementation from an approved .ai/STORE-BRIEF.md.
+- Generating storefront, backend, and admin scope from a single source of truth.
+
+## Preconditions
+- .ai/STORE-BRIEF.md should exist.
+- If it is missing, create it first using the ecommerce brief preparation workflow unless the user explicitly wants both steps in one run.
+
+## Required workflow
+1. Read .ai/STORE-BRIEF.md first.
+2. Create or update `AGENTS.md` from the brief before application code.
+3. Before any serious backend or frontend modification, create a timestamped snapshot under .backup/ and keep that folder append-only.
+4. Validate that the brief covers the sections in [build checklist](./assets/build-checklist.md).
+5. Establish a scalable folder structure for backend and frontend before adding large amounts of code.
+6. Build backend contracts and schema first.
+7. Build storefront flows next.
+8. Build admin panel or back office after the storefront contracts are stable.
+9. Finish with QA states, responsive behavior, motion, and asset handling.
+
+## Constraints
+- Do not contradict .ai/STORE-BRIEF.md without surfacing the conflict.
+- Do not skip admin scope unless the brief explicitly excludes it.
+- Do not leave core commerce flows as placeholders when the brief already defines them.
+- Keep models, services, config, routing, UI, and integration code in dedicated folders instead of mixing layers.
+
+## References
+- [build checklist](./assets/build-checklist.md)

site-fullstack/.github/skills/ecommerce-build-from-brief/assets/build-checklist.md

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+# Build Checklist
+
+Before implementation, confirm that .ai/STORE-BRIEF.md contains enough detail for:
+
+- Repo mode and current repo responsibilities.
+- Backend stack and database choice.
+- Frontend stack and rendering assumptions.
+- Storefront pages and flows.
+- Auth model and cart model.
+- Admin modules and staff roles.
+- Catalog entities and filtering model.
+- Order or lead flow.
+- Integrations and external dependencies.
+- Visual direction and asset status.
+- AGENTS.md plan.
+
+If one of these is materially missing, ask a focused follow-up question or record the implementation assumption before building.