Add English translations for all 379 recipe and tip files

Use dotlang AI translation (aiursoft-instruct:latest via Ollama) to
translate all Chinese content to English under en/ subfolder:
- en/dishes/: all recipe categories (aquatic, breakfast, condiment,
  dessert, drink, meat_dish, semi-finished, soup, staple, vegetable_dish)
- en/tips/: learn/ and advanced/ cooking guides
- en/README.md, en/CONTRIBUTING.md, en/CODE_OF_CONDUCT.md

The mkdocs-static-i18n plugin (docs_structure: folder) serves Chinese
at the root and English at /en/, with a language switcher in the UI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

en/dishes/soup/黄瓜皮蛋汤.md

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+# How to Make Cucumber and Century Egg Soup
+
+Cucumber and century egg soup is a quick and easy homemade dish, with a light flavor and a hint of roasted aroma. It's comforting for both the heart and stomach without being greasy. Even beginners in the kitchen can make it with ease!
+
+Estimated Cooking Difficulty: ★★
+
+## Essential Ingredients and Tools
+
+- Cucumber
+- Century egg
+- Garlic
+- Green onion
+- Cooking oil (pork fat is recommended)
+- Salt
+- Chicken bouillon powder (optional)
+
+## Calculation
+
+Before each preparation, decide how many servings you want to make. One serving is enough for 2 people.
+
+Per serving:
+
+- 1 cucumber
+- 2 century eggs
+- 2 cloves of garlic
+- Green onion
+- 10-15 g of cooking oil
+- 2-3 g of salt
+- 0.5-1 g of chicken bouillon powder
+- 400-500 ml of water
+
+## Instructions
+
+- Wash the cucumber and slice it into thin pieces about 0.5-1.2 mm thick.
+- Wash the green onion and mince it. Use the flat side of a knife to crush the garlic cloves, then peel and cut them in half.
+- Peel the century eggs and cut each into 6-8 pieces. Pour oil into a pot and add the sliced century eggs and garlic.
+- Stir-fry over low heat until the century eggs and garlic turn slightly golden on the surface. Add water, then increase the heat to bring to a boil.
+- Add the cucumber slices. Once the water boils again, immediately turn off the heat and add salt and chicken bouillon powder for seasoning before serving.
+- Pour into bowls and garnish with chopped green onions.
+
+## Additional Tips
+
+- You can choose whether or not to peel the cucumber based on your preference.
+- Thin cucumber slices can be made using a peeler.
+- Lightly coat the knife with sesame oil when cutting century eggs to prevent sticking.
+- Reference: [【Cucumber and Century Egg Soup Step-by-Step Guide】Spring is Here__Xiachufang](https://www.xiachufang.com/recipe/103991291/)
+
+If you encounter any issues or have suggestions for improvement while following this guide, please submit an Issue or Pull request.