feat(proxy): T-P0 代理层骨架（包结构/DDL/门控挂载/单进程校验）

- gateway/proxy/ 十文件：config（ProxyConfig：元->毫元加载期换算 D-P1、差异化售价、
  桶/峰谷/限流/semcache 配置）/ errors（8 类 HTTP 语义异常）/ ledger（四表两索引 DDL，
  WAL，ReviewQueue 连接纪律）/ auth·pricing·normalizer·semcache·upstream（§6 签名占位）
  / routes（/proxy/v1/models OpenAI 形状）/ __init__（build_proxy_router 组装点）
- settings DEFAULTS 增 proxy 段（enabled 默认 False，D-P7）
- api.py 首次 include_router（enabled 门控 + 装配失败不拖垮主应用）
- serve.py workers>1 拒绝启动（D-P9：WEB_CONCURRENCY/UVICORN_WORKERS 校验）
- 测试 +4（门控 404/DDL 幂等/毫元换算/池模型列表），全量 322 passed

tests/test_proxy_routes.py

@@ -0,0 +1,87 @@
+"""代理层骨架测试（T-P0）：enabled 门控 / DDL / 独立挂载的 models 端点。"""
+import pytest
+
+pytest.importorskip("fastapi")
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+import gateway.api as ga
+from gateway.proxy.config import ProxyConfig, build_proxy_config
+from gateway.proxy.ledger import Ledger
+
+
+def test_proxy_disabled_by_default_404():
+    """D-P7：默认 enabled=False -> 全局 app 不注册任何 /proxy 路由。"""
+    client = TestClient(ga.app)
+    assert client.get("/proxy/v1/models").status_code == 404
+    assert client.post("/proxy/v1/chat/completions", json={}).status_code == 404
+    assert client.get("/proxy/admin/stats").status_code == 404
+
+
+def test_ddl_creates_tables_and_indexes(tmp_path):
+    """四表 + 两索引幂等创建（WAL）。"""
+    led = Ledger.init_db(tmp_path / "proxy.sqlite3")
+    tables = set(led.table_names())
+    for t in ("students", "proxy_keys", "usage_ledger", "semcache"):
+        assert t in tables
+    idx = set(led.index_names())
+    assert "idx_semcache_bucket" in idx
+    assert "idx_ledger_ts" in idx
+    # 幂等重建
+    led2 = Ledger.init_db(tmp_path / "proxy.sqlite3")
+    assert "semcache" in set(led2.table_names())
+
+
+def test_build_proxy_config_defaults_and_milli_conversion():
+    """缺省值兜底 + 元/1M -> 毫元/1M 加载期换算（D-P1）。"""
+    from gateway.settings import DEFAULTS
+    cfg = build_proxy_config(DEFAULTS)      # DEFAULTS 自带 deepseek-chat 价格示例
+    assert cfg.enabled is False
+    assert "default" in cfg.buckets
+    assert cfg.sale_in == 0.5 and cfg.sale_out == 0.8     # 差异化定价
+    # 自带 DEFAULTS 的 deepseek-chat 价格：3.0 元 -> 3000 毫元
+    p = cfg.price("deepseek-chat")
+    assert p is not None
+    assert p.in_miss == 3000
+    assert p.in_hit == 100            # 0.1 元 -> 100 毫元
+    assert p.out == 9000
+
+    # in_hit 缺省 = in_miss / 30（D-P3）
+    cfg2 = build_proxy_config({"proxy": {
+        "pricing": {"some-model": {"in_miss": 3.0, "out": 9.0}}}})
+    p2 = cfg2.price("some-model")
+    assert p2.in_hit == 100           # 3000 // 30
+
+    # 桶解析回落 default
+    assert cfg.bucket("ghost").name == "default"
+
+
+def test_enabled_router_lists_pool_models(tmp_path, monkeypatch):
+    """enabled=True 独立挂载：/proxy/v1/models 返回池内非 mock 模型（OpenAI 形状）。"""
+    import gateway.model_pool as mp
+    from gateway.model_pool import PoolStore
+    mp.reset_pool()
+    monkeypatch.setattr(mp, "_store", PoolStore(path=tmp_path / "pool.json"))
+    mp.get_pool().upsert({
+        "id": "up1", "name": "云端", "tier": "budget", "backend": "openai",
+        "base_url": "https://api.example.com", "model": "deepseek-chat",
+        "price_in": 0.1, "price_out": 0.1, "enabled": True})
+    mp.get_pool().upsert({
+        "id": "mk", "name": "模拟", "tier": "local", "backend": "mock",
+        "model": "mock", "enabled": True})            # mock 不应出现
+
+    cfg = build_proxy_config({"proxy": {"enabled": True,
+                                        "db_path": str(tmp_path / "p.sqlite3")}})
+    app = FastAPI()
+    app.include_router(__import__("gateway.proxy", fromlist=["x"]).build_proxy_router(
+        cfg, mp.get_pool()))
+    client = TestClient(app)
+    r = client.get("/proxy/v1/models")
+    assert r.status_code == 200
+    data = r.json()
+    assert data["object"] == "list"
+    ids = [m["id"] for m in data["data"]]
+    assert ids == ["deepseek-chat"]
+    assert data["data"][0]["owned_by"] == "campus-proxy"
+    mp.reset_pool()