feat: 实现多语言文档架构

- 创建 docs/zh/ 和 docs/en/ 目录结构
- 迁移文档至多语言目录，添加中英文切换链接
- 创建 README_EN.md 英文版本
- 更新 README.md 添加语言切换链接
- 删除旧文档和临时文件

docs/en/ADAPTER.md

@@ -0,0 +1,104 @@
+**中文** | [English](../zh/ADAPTER.md)
+
+# Lua Adapter — LLM Source Adaptation Guide
+
+Each LLM API source corresponds to a Lua script, responsible for request transformation (Go unified format → API format) and response transformation (API format → Go unified format).
+
+## Adapter Contract
+
+The Lua script must return a table containing the following fields and functions:
+
+```lua
+local adapter = {}
+
+-- Metadata
+adapter.name = "my_provider"   -- Unique identifier, matches adapter field in config
+adapter.version = "2.0.0"
+adapter.endpoint = "/v1/chat/completions"   -- API path, appended to base_url
+adapter.headers = {}                        -- Additional HTTP request headers
+
+-- Request transformation: Go → API
+function adapter.transform_request(raw_json)
+    -- raw_json: Go's CompletionRequest JSON string
+    -- Returns: JSON string to send to API
+    return transformed_json
+end
+
+-- Response transformation: API → Go
+function adapter.transform_response(raw_json)
+    -- raw_json: API's raw response JSON string
+    -- Returns: Unified CompletionResponse JSON string
+    -- Unified format:
+    --   { content: "", finish_reason: "", token_usage: { prompt: N, completion: N, total: N }, tool_calls?: [...] }
+    return unified_json
+end
+
+-- Stream chunk transformation (optional)
+function adapter.transform_stream_chunk(raw_line)
+    -- raw_line: JSON string after data: in SSE
+    -- Returns: JSON of { content: "", done: bool }, return "" to skip this chunk
+    return chunk_json
+end
+
+return adapter
+```
+
+## Unified CompletionRequest Format (Go → Adapter)
+
+```json
+{
+  "model": "deepseek-v4-flash",
+  "messages": [
+    { "role": "system", "content": "..." },
+    { "role": "user", "content": "..." },
+    { "role": "assistant", "content": "...", "tool_calls": [...] }
+  ],
+  "temperature": 0.7,
+  "max_tokens": 4096,
+  "stream": false,
+  "tools": [...],
+  "tool_choice": "auto"
+}
+```
+
+## Unified CompletionResponse Format (Adapter → Go)
+
+```json
+{
+  "content": "Response content",
+  "finish_reason": "stop",
+  "token_usage": { "prompt": 10, "completion": 20, "total": 30 },
+  "tool_calls": [
+    { "id": "call_xxx", "type": "function", "name": "tool_name", "arguments": { "key": "val" } }
+  ]
+}
+```
+
+## Lua VM Built-in Functions
+
+`json.encode(table)` — Encode Lua table to JSON string
+
+`json.decode(string)` — Decode JSON string to Lua table
+
+`log(level, message)` — Output log (level: info/warn/error)
+
+## Adapting Typical APIs
+
+| API | endpoint | auth method | Format differences |
+|-----|----------|-------------|-------------------|
+| **OpenAI** | `/chat/completions` | `Authorization: Bearer <key>` | Standard OpenAI format |
+| **DeepSeek** | `/chat/completions` | `Authorization: Bearer <key>` | OpenAI compatible, forces temperature=0 |
+| **Anthropic** | `/v1/messages` | `x-api-key: <key>` | Messages API, system message separated, content as block array |
+| **Gemini** | `/v1/models/{model}:generateContent` | `?key=<key>` or Bearer | contents/parts format, role uses model instead of assistant |
+| **Mistral** | `/v1/chat/completions` | `Authorization: Bearer <key>` | OpenAI compatible |
+| **Groq** | `/openai/v1/chat/completions` | `Authorization: Bearer <key>` | OpenAI compatible |
+| **GitHub Models** | `/chat/completions` | `Authorization: Bearer <pat>` | OpenAI compatible |
+| **Ollama** | `/api/chat` | None | Different options format |
+
+## Steps to Add a New Source
+
+1. Create `<name>.lua` under `internal/lua/adapters/`
+2. Script defines `transform_request` and `transform_response`
+3. (Optional) Define `transform_stream_chunk` for streaming support
+4. Build verification: `go build ./cmd/homed/`
+5. Test verification: `go test ./...`