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/meat_dish/黑椒牛柳/黑椒牛柳.md

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+# How to Make Black Pepper Beef
+
+![Finished Black Pepper Beef](./black_pepper_beef.jpg)
+
+Black Pepper Beef is a simple and easy-to-make dish. It offers a balanced mix of vegetables and meat, is rich in protein, and has a flavor profile suitable for most people. Beginners can typically complete it in under 1 hour.
+
+Estimated Cooking Difficulty: ★★★★
+
+## Essential Ingredients and Tools
+
+- Beef (beef tenderloin or steak meat can be used)
+- Onion
+- Bell peppers (red/yellow)
+- Cornstarch
+- Black pepper (powder)
+- Black pepper marinade
+- Salt
+- Peanut oil
+
+Note: The powder and marinade can be used interchangeably. Please refer to the instructions on the food packaging for specific quantities.
+
+It is recommended to use a non-stick pan.
+
+## Calculations
+
+Determine how many servings you plan to make before each preparation. One serving is sufficient for 2-3 people.
+
+Total Amounts:
+
+- Beef amount = Servings * 100 grams (adjust according to the diners' appetite and pan capacity)
+- Onion amount = Servings * 1/12 of an onion (i.e., approximately 1/4 for 3 people)
+- Bell pepper amount = Servings * 1/12 of a pepper (i.e., approximately 1/4 for 3 people)
+- Salt amount = Servings * 1 gram
+- Cornstarch = Servings * 3 grams
+- Black pepper marinade = Marinate according to the ratio specified on the purchased product's instructions
+- Black pepper powder = Servings * 1 gram (in practice, sprinkle as desired)
+- Peanut oil = Servings * 10 ml (in practice, the amount of oil varies based on the quantity of food; adjust proportionally if you change the amount of beef)
+
+Use the above conditions to calculate the ratio of raw materials to be used.
+
+## Instructions
+
+- Cut the beef into strips. The length should ideally be controlled to under 8 cm, with a thickness of about 5-10 mm and a width of about 1 cm (strict requirements are not necessary).
+- Marinate the beef using the marinade. Mix well and let it sit. Refer to the product instructions for the amount and time; you may extend the time but not shorten it.
+- If using a liquid marinade, sprinkle a layer of black pepper powder three minutes before the marinating ends, then add the cornstarch. Mix well again and let it sit for 20 minutes.
+- Turn on the heat, heat the pan, and add the peanut oil.
+- When you see a wisp of smoke coming from the oil in the pan, add the beef and stir-fry.
+- Use medium-high heat and stir-fry for 2 minutes until the outside of the beef changes color (i.e., no obvious red blood remains; if red blood is visible, it indicates insufficient stir-frying) (be careful of oil splatters here).
+- Add the onion and bell peppers, and stir-fry for 2 minutes.
+- Add salt, sprinkle another portion of black pepper powder, stir-fry for 30 seconds, and mix well.
+- Turn off the heat once the onion has softened, remove from the pan, and plate.
+
+## Additional Content
+
+If you follow this guide's process and find issues or have suggestions for improvement, please submit an Issue or Pull request.