refactor: 重构 algorithm 为 ai-core 代码解析服务

- 新增 ai-core 目录，包含代码解析核心服务
- 添加 proto 定义、parser、service 模块
- 添加启动脚本和依赖配置

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ai-core/proto/document_parser.proto

@@ -0,0 +1,47 @@
+syntax = "proto3";
+
+package docparser;
+
+option go_package = "x-agents/proto/docparser";
+
+service DocumentParser {
+  rpc ParseDocument(ParseRequest) returns (ParseResponse);
+  rpc GetSupportedFormats(Empty) returns (SupportedFormatsResponse);
+  rpc GetEngines(Empty) returns (EnginesResponse);
+}
+
+message ParseRequest {
+  string file_url = 1;
+  string file_name = 2;
+  string file_type = 3;
+  string parser_engine = 4;
+  map<string, string> engine_overrides = 5;
+}
+
+message ParseResponse {
+  bool success = 1;
+  string content = 2;
+  string message = 3;
+  int32 content_length = 4;
+  string file_type = 5;
+  string parser_engine = 6;
+}
+
+message Empty {}
+
+message SupportedFormatsResponse {
+  repeated string file_types = 1;
+  map<string, string> file_type_descriptions = 2;
+}
+
+message EnginesResponse {
+  repeated EngineInfo engines = 1;
+}
+
+message EngineInfo {
+  string name = 1;
+  string description = 2;
+  repeated string supported_file_types = 3;
+  bool available = 4;
+  string unavailable_reason = 5;
+}