v0.7.3: 重构 Provider 层 + 计算层隔离 + Cleaner/NoMemory 架构

- 删除 OpenAIProvider/OllamaProvider 死代码，LuaAdaptedProvider 独存
- DisableThinking 从 ExtraBody 移到 CompletionRequest 顶层字段
- ContextWindow 从 Provider 签名移到 BaseConfig/ModelContextWindow() 统管
- 确认 CleanText 仅做基本空白 trim，QQ 模板剥离归插件 Cleaner
- Cleaner/NoMemory 仅作用于向量计算和 jieba 分词层，原文不变
- context.ContextEvent/Doc.Content 始终保存原文
- 删除 nlp/download.go 死代码
- media.go: context.Background() -> a.ctx 级联
- clawhubadapter: HTTP 超时
- cut.go: 跨平台 mod cache 路径 (GOMODCACHE->GOPATH->HomeDir)
- bridge_e2e_test: 移除未用 runtime import
- lua 适配器: disable_thinking 传参

internal/lua/adapters/groq.lua

@@ -13,6 +13,8 @@ function adapter.transform_request(raw_body)
     req.temperature = req.temperature or 0.7
     req.max_tokens = req.max_tokens or 4096
     req.stream = req.stream or false
+    req.disable_thinking = nil
+    req.extra_body = nil
     return json.encode(req)
 end