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-foundation/assets/image-prompt-template.md

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+# Image Prompt Template
+
+Use this template when the project needs visuals but the final assets do not exist yet.
+
+Prompt structure:
+- Brand and market context
+- Exact subject
+- Composition and camera distance
+- Aspect ratio and framing
+- Background and props
+- Lighting and mood
+- Material, texture, and styling details
+- Output quality cues
+- Negative constraints
+
+Example skeleton:
+Create a premium ecommerce hero image for a {brand type} store selling {product type}. Show {subject} in a {composition} composition, shot for a {aspect ratio} canvas. Use a {background style} background with {lighting style} lighting. Visual tone: {keywords}. Include room for headline text. Avoid watermarks, distorted hands, broken anatomy, cluttered backgrounds, oversaturated colors, and unreadable product details.