feat: 将插件 stdin 协议定为 v1，并按声明注入凭据

进程外插件改为只读环境变量和自身配置，避免读宿主 appsettings；宿主按 plugin.json 声明注入 LLM / OpenWeather 等凭据。

MAF1.Web/PluginHost/CredentialStore.cs

@@ -32,18 +32,16 @@ public sealed class CredentialPublicView
 /// </summary>
 public sealed class CredentialStore
 {
-    private readonly IConfiguration _config;
     private readonly Dictionary<string, CredentialRecord> _named = new(StringComparer.OrdinalIgnoreCase);
 
     public CredentialStore(IConfiguration config)
     {
-        _config = config;
         LlmOptions llm = AgentFactory.Load(config);
         _named["llm-default"] = new CredentialRecord
         {
             Id = "llm-default",
             Name = "系统默认模型",
-            Type = "openai-compatible",
+            Type = PluginCredentialTypes.OpenAiCompatible,
             Endpoint = llm.Endpoint,
             ApiKey = llm.ApiKey,
             Model = llm.Model,
@@ -53,23 +51,38 @@ public sealed class CredentialStore
         foreach (IConfigurationSection child in section.GetChildren())
         {
             string id = child.Key;
-            string type = child["type"] ?? "openai-compatible";
+            string type = child["type"] ?? PluginCredentialTypes.OpenAiCompatible;
             bool useLlm = string.Equals(child["source"], "llm-section", StringComparison.OrdinalIgnoreCase)
                 || child.GetValue("useLlmSection", false);
-            CredentialRecord fallback = _named.GetValueOrDefault("llm-default")!;
+            CredentialRecord fallback = _named["llm-default"];
+            Dictionary<string, string> extra = new(StringComparer.OrdinalIgnoreCase);
+            foreach (IConfigurationSection extraChild in child.GetSection("extra").GetChildren())
+            {
+                if (!string.IsNullOrWhiteSpace(extraChild.Value))
+                {
+                    extra[extraChild.Key] = extraChild.Value;
+                }
+            }
+
+            string apiKey = First(
+                child["apiKey"],
+                useLlm ? fallback.ApiKey : null,
+                PluginCredentialTypes.IsOpenWeather(type) ? Environment.GetEnvironmentVariable("OPENWEATHER_API_KEY") : null);
+
             _named[id] = new CredentialRecord
             {
                 Id = id,
                 Name = child["name"] ?? id,
                 Type = type,
                 Endpoint = First(child["endpoint"], useLlm ? fallback.Endpoint : null),
-                ApiKey = First(child["apiKey"], useLlm ? fallback.ApiKey : null),
+                ApiKey = apiKey,
                 Model = First(child["model"], useLlm ? fallback.Model : null),
+                Extra = extra,
             };
         }
     }
 
-    /// <summary>给前端的列表。Endpoint 目前未打码（学习项目）；ApiKey 绝不会出现在这里。</summary>
+    /// <summary>给前端的列表。ApiKey 绝不会出现在这里。</summary>
     public IReadOnlyList<CredentialPublicView> ListPublic()
         => _named.Values
             .OrderBy(item => item.Id, StringComparer.OrdinalIgnoreCase)
@@ -91,6 +104,23 @@ public sealed class CredentialStore
         throw new InvalidOperationException($"找不到凭据 `{id}`。请在 appsettings.json 的 Credentials 中配置，或改用 llm-default。");
     }
 
+    /// <summary>按插件声明的 type 取凭据。preferredId 类型不匹配时不会凑合用。</summary>
+    public CredentialRecord? TryResolveForType(string declaredType, string? preferredId)
+    {
+        if (!string.IsNullOrWhiteSpace(preferredId) && _named.TryGetValue(preferredId, out CredentialRecord? named))
+        {
+            if (!PluginCredentialTypes.Matches(declaredType, named.Type))
+            {
+                throw new InvalidOperationException(
+                    $"凭据 `{preferredId}` 的类型是 `{named.Type}`，插件声明需要 `{declaredType}`。");
+            }
+
+            return named;
+        }
+
+        return _named.Values.FirstOrDefault(item => PluginCredentialTypes.Matches(declaredType, item.Type));
+    }
+
     public PluginCredentialPayload ToPayload(CredentialRecord record)
         => new()
         {