重构并拆分项目

service/migrations/20260601000004_llm_usage.sql

@@ -0,0 +1,15 @@
+-- LLM Token 用量统计
+CREATE TABLE IF NOT EXISTS llm_usage (
+    id BIGSERIAL PRIMARY KEY,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    user_id TEXT NOT NULL DEFAULT '',
+    model TEXT NOT NULL DEFAULT '',
+    provider TEXT NOT NULL DEFAULT 'deepseek',
+    prompt_tokens INTEGER NOT NULL DEFAULT 0,
+    completion_tokens INTEGER NOT NULL DEFAULT 0,
+    total_tokens INTEGER NOT NULL DEFAULT 0,
+    cache_hit_tokens INTEGER NOT NULL DEFAULT 0,
+    cache_miss_tokens INTEGER NOT NULL DEFAULT 0
+);
+
+CREATE INDEX IF NOT EXISTS idx_llm_usage_created ON llm_usage (created_at DESC);