refactor: 重构目录结构以支持 i18n

创建 'i18n' 目录以存放多语言内容。将所有现有的中文内容（文档、提示词、技能、README）移动到 'i18n/zh/' 中。添加了新的根 README 作为语言入口，并为英文（'en'）翻译创建了占位符结构。

skills/coingecko/references/nfts.md

@@ -1,38 +0,0 @@
-# Coingecko - Nfts
-
-**Pages:** 2
-
----
-
-## NFTs Collection Data by ID
-
-**URL:** llms-txt#nfts-collection-data-by-id
-
-Source: https://docs.coingecko.com/v3.0.1/reference/nfts-id
-
-v3.0.1/reference/api-reference/coingecko-demo.json get /nfts/{id}
-This endpoint allows you to **query all the NFT data (name, floor price, 24hr volume ...) based on the NFT collection ID**
-
-* Cache / Update Frequency: every 60 seconds for all the API plans.
-</Note>
-
----
-
-## NFTs List (ID Map)
-
-**URL:** llms-txt#nfts-list-(id-map)
-
-Source: https://docs.coingecko.com/v3.0.1/reference/nfts-list
-
-v3.0.1/reference/api-reference/coingecko-demo.json get /nfts/list
-This endpoint allows you to **query all supported NFTs with ID, contract address, name, asset platform ID and symbol on CoinGecko**
-
-* You may use this endpoint to query the list of NFTs for other endpoints that contain params like `id` (NFT collection's id) as well as `asset_platform_id` and `contract_address`.
-  * You may include values such as `per_page` and `page` to specify how many results you would like to show in the responses per page and which page of responses you would like to show.
-</Tip>
-
-* The responses are paginated to 100 items.
-  * Cache / Update Frequency: every 5 minutes for all the API plans.
-</Note>
-
----