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-code-review/assets/python-quality-matrix.md

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+# Python Quality Matrix
+
+## Configuration detection
+- Read `pyproject.toml` first.
+- Detect the configured Python version.
+- Detect `mypy`, `ty`, `ruff`, `deptry`, `pytest`, and formatter configuration.
+
+## Review rules
+- If `mypy` is configured, check the actual options before judging missing annotations or strictness violations.
+- If `ty` is configured, use its configured expectations and error model.
+- If both exist, respect whichever toolchain the project clearly treats as authoritative, and flag inconsistent duplication.
+- If `ruff` is configured, review for meaningful rule violations, not cosmetic churn.
+- If `deptry` is configured, verify dependency placement, unused dependencies, and hidden transitive reliance.
+
+## Modern Python usage
+- Use modern typing syntax only when the configured Python version supports it.
+- Prefer `typing.Self`, `typing.TypeAliasType`, `typing.override`, `collections.abc` imports, `match`, `enum.StrEnum`, dataclass slots, and other newer features only when they improve clarity and compatibility.
+- Do not suggest a newer language feature that the configured interpreter cannot run.
+
+## Common harsh checks
+- Weak or missing type boundaries.
+- Hidden `Any` spread.
+- Async misuse.
+- Leaky ORM or transport models.
+- Overly dynamic code that defeats static analysis.
+- Wrong dependency classification.