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-store-evolution/SKILL.md

@@ -0,0 +1,28 @@
+---
+name: ecommerce-store-evolution
+description: 'Extend or refactor an existing ecommerce project with FastAPI, React, Next.js, admin panel, catalog changes, AGENTS.md updates, and safer rollout planning.'
+argument-hint: 'Describe the current project and the features or refactor you need'
+---
+# Ecommerce Store Evolution
+
+## When to use
+- Extending an existing online store.
+- Adding a new admin module, catalog flow, account area, or backend capability.
+- Refactoring a commerce codebase without losing its current conventions.
+
+## Procedure
+1. Audit the existing repo and compare it with [extension checklist](./assets/extension-checklist.md).
+2. Create or update AGENTS.md if the repo lacks clear delivery rules.
+3. Before serious backend or frontend edits, create a timestamped snapshot under .backup/ and never modify or delete older backup entries.
+4. Preserve stable patterns and change only what is necessary.
+5. Write a small implementation plan using [rollout plan template](./assets/rollout-plan-template.md).
+6. Implement backend and frontend changes with regression awareness.
+
+## Architecture rule
+- New backend code should go into the proper layers such as routers, models, schemas, services, repositories, config, and tests.
+- New frontend code should go into the proper layers such as app or routes, pages, features, entities, shared components, api or services, hooks, config, styles, and tests.
+- If the current project is too flat or mixed, improve the structure incrementally instead of adding more chaos.
+
+## References
+- [extension checklist](./assets/extension-checklist.md)
+- [rollout plan template](./assets/rollout-plan-template.md)