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-seo-review/assets/severity-rubric.md

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+# Severity Rubric
+
+## Critical
+- Likely to block crawling or indexation of important commercial pages.
+- Likely to create large-scale duplicate or canonical errors.
+- Likely to break structured data trust on strategic templates.
+
+## High
+- Likely to materially reduce rankings, CTR, or discoverability on important page groups.
+- Affects high-value categories, product templates, or core internal-link systems.
+
+## Medium
+- Noticeable quality gap or missed opportunity, but not a severe blocker.
+- Often template-level improvements, partial metadata gaps, or incomplete linking coverage.
+
+## Low
+- Nice-to-have improvements, polish items, or issues with limited SEO impact.
+
+## Finding format
+- Severity
+- Area
+- Affected page type or module
+- What is wrong
+- Why it matters
+- Recommended fix
+- Validation note if runtime confirmation is still needed