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/contract.md

@@ -1,23 +0,0 @@
-# Coingecko - Contract
-
-**Pages:** 1
-
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-
-## NFTs Collection Data by Contract Address
-
-**URL:** llms-txt#nfts-collection-data-by-contract-address
-
-Source: https://docs.coingecko.com/v3.0.1/reference/nfts-contract-address
-
-v3.0.1/reference/api-reference/coingecko-demo.json get /nfts/{asset_platform_id}/contract/{contract_address}
-This endpoint allows you to **query all the NFT data (name, floor price, 24hr volume ...) based on the NFT collection contract address and respective asset platform**
-
-* You may also obtain the asset platform id and contract address through [/nfts/list](/v3.0.1/reference/nfts-list) endpoint.
-</Tip>
-
-* Solana NFT & Art Blocks are not supported for this endpoint, please use [/nfts/\{id}](/v3.0.1/reference/nfts-id) endpoint instead.
-  * Cache / Update Frequency: every 60 seconds for all the API plans.
-</Note>
-
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