Build a Recipe Sharing API

Problem/Feature Description

A cooking community wants a backend API for sharing recipes. Build it in Go using the standard library.

Resources:

• Recipe: { id, title, author, ingredients (list of strings), instructions, servings, prepTimeMinutes, createdAt }
• Rating: { id, recipeId, score (1-5), comment, createdAt }

Endpoints:

• GET /api/recipes -- list all recipes
• GET /api/recipes/{id} -- get a recipe with its average rating
• POST /api/recipes -- create a recipe (title, author, ingredients, instructions all required; servings > 0)
• PUT /api/recipes/{id} -- update a recipe (only the original author can update -- pass X-User header)
• DELETE /api/recipes/{id} -- delete a recipe (only the original author)
• POST /api/recipes/{id}/ratings -- add a rating to a recipe (score 1-5 required)
• GET /api/recipes/{id}/ratings -- list ratings for a recipe

Use in-memory storage.

Output Specification

Produce:

• main.go -- entry point
• Source files for handlers, models, middleware, errors
• go.mod

You may split across files as you see fit.