feat: 新增 Agent、Memory、Skill 模块

- handler: agent_handler, memory_handler, skill_handler
- model: agent.go, skill.go
- repository: agent_repo, skill_repo
- service: agent_service, memory_service, skill_service
- 新增 migrations 目录

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

server/migrations/agent_system.sql

@@ -0,0 +1,63 @@
+-- =====================================================
+-- Agent System Database Migration
+-- Run this script if you want vector-based memory storage
+-- Note: Requires pgvector extension for PostgreSQL
+-- =====================================================
+
+-- Enable pgvector extension (PostgreSQL only)
+-- CREATE EXTENSION IF NOT EXISTS vector;
+
+-- Agent Memory with Vector Embedding (Optional - for vector search)
+-- This table is optional. If not using vector search, use agent_memories table instead.
+-- CREATE TABLE IF NOT EXISTS agent_memory_vectors (
+--     id VARCHAR(191) PRIMARY KEY,
+--     agent_id VARCHAR(191) NOT NULL,
+--     user_id VARCHAR(191),
+--     content TEXT NOT NULL,
+--     embedding vector(1536),  -- Adjust dimension based on your embedding model
+--     memory_type VARCHAR(20), -- experience/preference/conversation
+--     importance INT DEFAULT 5,
+--     created_at DATETIME(3),
+--     updated_at DATETIME(3),
+--     INDEX idx_agent_vector USING ivfflat (agent_id, embedding vector_cosine_ops),
+--     INDEX idx_importance (agent_id, importance DESC)
+-- );
+
+-- For MySQL (without vector support, use text search instead)
+CREATE TABLE IF NOT EXISTS agent_memory_vectors (
+    id VARCHAR(191) PRIMARY KEY,
+    agent_id VARCHAR(191) NOT NULL,
+    user_id VARCHAR(191),
+    content TEXT NOT NULL,
+    embedding_text TEXT,  -- Store serialized vector for MySQL
+    memory_type VARCHAR(20),
+    importance INT DEFAULT 5,
+    created_at DATETIME(3),
+    updated_at DATETIME(3),
+    INDEX idx_agent_memory_agent (agent_id),
+    INDEX idx_agent_memory_user (agent_id, user_id),
+    INDEX idx_importance (agent_id, importance DESC)
+);
+
+-- Agent Task Indexes
+CREATE INDEX IF NOT EXISTS idx_agent_tasks_agent_user ON agent_tasks(agent_id, user_id);
+CREATE INDEX IF NOT EXISTS idx_agent_tasks_session ON agent_tasks(session_id);
+CREATE INDEX IF NOT EXISTS idx_agent_tasks_status ON agent_tasks(status);
+CREATE INDEX IF NOT EXISTS idx_agent_tasks_created ON agent_tasks(created_at DESC);
+
+-- Agent Team Indexes
+CREATE INDEX IF NOT EXISTS idx_agent_team_supervisor ON agent_teams(supervisor_agent_id);
+CREATE INDEX IF NOT EXISTS idx_agent_team_member ON agent_teams(member_agent_id);
+
+-- Agent Memory Indexes
+CREATE INDEX IF NOT EXISTS idx_agent_memory_agent ON agent_memories(agent_id);
+CREATE INDEX IF NOT EXISTS idx_agent_memory_user ON agent_memories(agent_id, user_id);
+CREATE INDEX IF NOT EXISTS idx_agent_memory_type ON agent_memories(memory_type);
+
+-- Agent Skills Indexes
+CREATE INDEX IF NOT EXISTS idx_agent_skills_agent ON agent_skills(agent_id);
+CREATE INDEX IF NOT EXISTS idx_agent_skills_skill ON agent_skills(skill_id);
+
+-- Agent Knowledge Base Indexes
+CREATE INDEX IF NOT EXISTS idx_agent_kb_agent ON agent_knowledge_bases(agent_id);
+CREATE INDEX IF NOT EXISTS idx_agent_kb_kb ON agent_knowledge_bases(knowledge_base_id);