feat: Phase 0 — monorepo 骨架 + 全表迁移 + FastAPI/Next 骨架 + CI

- uv(workspace) + pnpm monorepo；docker-compose(pg+api+web)
- SQLAlchemy 16 MVP 表 + Alembic 初版迁移(无漂移，users stub)
- FastAPI 骨架：统一错误信封(带 request_id) + structlog + /jobs/:id + OpenAPI
- Next.js 骨架：纸感主题 token + OpenAPI→TS 客户端代码生成(gen:api)
- CI(ruff/mypy/pytest + pg service + alembic 漂移校验)
- 四份设计规格(PRODUCT/UX/ARCHITECTURE/DEV_PLAN) + CLAUDE.md

packages/config/ww_config/settings.py

@@ -0,0 +1,29 @@
+"""应用配置（env 解析）。提供商注册/档位默认见后续阶段。"""
+
+from __future__ import annotations
+
+from functools import lru_cache
+
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
+
+    app_env: str = "dev"
+    log_json: bool = False
+    database_url: str = "postgresql+asyncpg://writer:writer@localhost:5432/writer"
+    database_url_sync: str = "postgresql+psycopg://writer:writer@localhost:5432/writer"
+    credential_enc_key: str = ""
+
+    # 档位默认（writer/analyst/light）——具体 provider:model 经 tier_routing 覆盖
+    tier_defaults: dict[str, str] = {
+        "writer": "deepseek:deepseek-chat",
+        "analyst": "deepseek:deepseek-chat",
+        "light": "deepseek:deepseek-chat",
+    }
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()