llm: 统一源接入层修复（对照 llmsproxy）

- provider: 新增 OpenAI-compatible 响应/流兜底解析，Lua adapter 异常时也能解析
  choices/message/tool_calls/usage（含 function.arguments 缺失、对象/字符串参数）
- 过滤无效 LLM 源（<nil>/空/缺 http(s) scheme），main 与 ReloadFromConfig 均跳过，
  避免 mocktest 等坏源污染 fallback 与 healthcheck
- adapter(openai/deepseek/groq/mistral/github/kimicode): 修 tool_calls 对
  nil function 的崩溃，兼容扁平/嵌套结构；openai 流透传 reasoning/tool_calls
- config: ToConfig 探活端点过滤无效 base_url，修复 supervisor 误报 LLM unreachable

internal/lua/adapters/groq.lua

@@ -41,14 +41,34 @@ function adapter.transform_response(raw_body)
             if type(ch.message.tool_calls) == "table" then
                 local tcs = {}
                 for _, tc in ipairs(ch.message.tool_calls) do
-                    local args_ok, args = pcall(json.decode, tc["function"].arguments)
-                    if not args_ok then args = {} end
-                    table.insert(tcs, {
-                        id = tc.id,
-                        type = tc.type or "function",
-                        name = tc["function"].name,
-                        arguments = args
-                    })
+                    local fn = tc["function"]
+                    local name = tc.name
+                    local raw_args = tc.arguments
+                    if type(fn) == "table" then
+                        name = fn.name or name
+                        raw_args = fn.arguments or raw_args
+                    end
+                    local args = {}
+                    if type(raw_args) == "table" then
+                        args = raw_args
+                    elseif type(raw_args) == "string" and raw_args ~= "" then
+                        local args_ok, decoded = pcall(json.decode, raw_args)
+                        if args_ok and type(decoded) == "table" then
+                            args = decoded
+                        elseif args_ok then
+                            args = { value = decoded }
+                        else
+                            args = { raw = raw_args }
+                        end
+                    end
+                    if name ~= nil and name ~= "" then
+                        table.insert(tcs, {
+                            id = tc.id,
+                            type = tc.type or "function",
+                            name = name,
+                            arguments = args
+                        })
+                    end
                 end
                 unified.tool_calls = tcs
             end