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/dessert/龟苓膏/龟苓膏.md

@@ -0,0 +1,47 @@
+# How to Make Guilinggao
+
+![Finished Guilinggao](./龟苓膏成品.jpg)
+
+Estimated Cooking Difficulty: ★★
+
+---
+
+## Ingredients and Tools Needed
+
+- Guilinggao powder: 25 g
+- Cold water: 120 ml
+- Boiling water: 500 ml
+- White granulated sugar: 100 g
+- Small pot
+- Stirring utensil
+- Mold or bowl
+
+---
+
+## Yield
+
+Each batch yields approximately 3–4 small bowls, suitable for 2–4 people.
+
+---
+
+## Instructions
+
+1. Pour 25 g of Guilinggao powder and 120 ml of cold water into a pot. Stir thoroughly until no lumps remain.
+2. In another container, add 100 g of white granulated sugar and pour in 500 ml of boiling water. Stir until the sugar is completely dissolved.
+3. Slowly pour the sugar water into the Guilinggao powder mixture, stirring immediately to prevent clumping.
+4. Transfer the mixture back into the pot. Heat over medium-low heat while stirring continuously to prevent sticking to the bottom.
+5. Cook until the liquid thickens and begins to form small bubbles, then remove from heat.
+6. Quickly pour the mixture into a mold and allow it to cool and set naturally. For better texture, refrigerate for 1–2 hours before serving.
+
+---
+
+## Additional Tips
+
+- Avoid moving the container while the Guilinggao is cooling, as this may affect its setting.
+- Avoid using high heat during cooking to prevent clumping or burning the bottom.
+- You can add honey, condensed milk, or fruit according to your personal preference.
+- The concentration of Guilinggao powder may vary slightly by brand. Refer to the package instructions and adjust the ratios as needed.
+
+---
+
+If you encounter any issues or have suggestions for improvement while following this guide, please submit an Issue or Pull Request.