feat: Add LSP plugin unit tests and frontend common initialization library

- Introduced `dstalk_lsp_plugin_test` for testing LSP plugin functionalities including `lsp_trim`, `lsp_frame_message`, and `lsp_parse_content_length`.
- Created `dstalk_frontend_common` static library to encapsulate shared initialization logic for frontend components (CLI, GUI, Web).
- Implemented configuration file discovery and service querying in `dstalk_frontend_init`.
- Added internal headers for LSP and Anthropic plugins to facilitate unit testing.
- Established a mailroom system for asynchronous message passing between stateless agents, enhancing coordination and context management.

dstalk_frontend_common/src/frontend_common.cpp

@@ -0,0 +1,124 @@
+// ============================================================================
+// dstalk_frontend_common — 实现
+// ============================================================================
+
+#include "dstalk_frontend_common.hpp"
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+// ---- 配置文件发现 ----
+
+static const char* discover_config(int argc, char* argv[],
+                                   const char* default_cfg,
+                                   const char* const* skip_flags)
+{
+    // 1) 从 argv 中查找首个非标志参数
+    if (argc >= 2 && argv) {
+        for (int i = 1; i < argc; ++i) {
+            bool is_skip = false;
+            if (skip_flags) {
+                for (int k = 0; skip_flags[k]; ++k) {
+                    if (std::strcmp(argv[i], skip_flags[k]) == 0) {
+                        is_skip = true;
+                        // 若该标志有值参数则多跳一个
+                        if (i + 1 < argc && argv[i + 1][0] != '-') ++i;
+                        break;
+                    }
+                }
+            }
+            if (!is_skip) return argv[i];
+        }
+    }
+
+    // 2) 回退：尝试默认配置文件
+    if (!default_cfg || default_cfg[0] == '\0') return nullptr;
+
+    const char* candidates[] = { default_cfg, nullptr };
+    for (int i = 0; candidates[i]; ++i) {
+        FILE* f = nullptr;
+#ifdef _WIN32
+        if (fopen_s(&f, candidates[i], "r") == 0 && f) {
+#else
+        f = std::fopen(candidates[i], "r");
+        if (f) {
+#endif
+            std::fclose(f);
+            return candidates[i];
+        }
+    }
+    return nullptr;
+}
+
+// ---- 主初始化 ----
+
+int dstalk_frontend_init(FrontendServices& svc,
+                         int argc, char* argv[],
+                         const char* default_cfg,
+                         const char* const* skip_flags)
+{
+    // (1) 发现并加载配置
+    const char* cfg = discover_config(argc, argv, default_cfg, skip_flags);
+    if (dstalk_init(cfg) != 0) {
+        std::fprintf(stderr, "[dstalk] 初始化失败\n");
+        return 1;
+    }
+
+    // (2) 查询 AI 服务
+    const char* provider = dstalk_config_get("ai.provider");
+    if (!provider || provider[0] == '\0') provider = "ai.deepseek";
+    svc.provider = provider;
+
+    svc.ai      = static_cast<const dstalk_ai_service_t*>(
+                      dstalk_service_query(provider, 1));
+    svc.session = static_cast<const dstalk_session_service_t*>(
+                      dstalk_service_query("session", 1));
+    svc.file_io = static_cast<const dstalk_file_io_service_t*>(
+                      dstalk_service_query("file_io", 1));
+    svc.tools   = static_cast<const dstalk_tools_service_t*>(
+                      dstalk_service_query("tools", 1));
+
+    const dstalk_context_service_t* ctx_svc =
+        static_cast<const dstalk_context_service_t*>(
+            dstalk_service_query("context", 1));
+    (void)ctx_svc; // 不强制使用，保留以备将来使用
+
+    if (!svc.ai) {
+        std::fprintf(stderr, "[dstalk] AI 服务未找到（请检查插件目录）\n");
+        return 2;
+    }
+    if (!svc.session) {
+        std::fprintf(stderr, "[dstalk] Session 服务未找到\n");
+        return 3;
+    }
+
+    // (3) 配置 AI 服务的默认值
+    const char* base_url = dstalk_config_get("api.base_url");
+    const char* api_key  = dstalk_config_get("api.api_key");
+    const char* model    = dstalk_config_get("api.model");
+
+    if (!base_url || base_url[0] == '\0') base_url = "https://api.deepseek.com/v1";
+    if (!model || model[0] == '\0')   model   = "deepseek-v4-pro";
+
+    svc.base_url = base_url;
+    svc.api_key  = api_key ? api_key : "";
+    svc.model    = model;
+
+    svc.ai->configure(provider, base_url,
+                      api_key ? api_key : "",
+                      model, 4096, 0.7);
+
+    svc.initialized = true;
+    return 0;
+}
+
+// ---- 会话历史回放 ----
+
+int dstalk_frontend_replay_history(FrontendServices& svc)
+{
+    if (!svc.session) return 0;
+    int count = 0;
+    const dstalk_message_t* msgs = svc.session->history(&count);
+    return count; // 调用方自行遍历并重建前端消息列表
+}