baseline: Clover 独立仓库首次基线提交

将 Clover 从上层产品包旧仓库中独立出来,建立专属版本控制。
当前状态=纵切片端到端已打通(登录→选品→出文出图→审核→下载包),
M1文案质量去套路化已验收。此提交作为后续按核销清单逐条修复的基线。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/alembic/env.py

@@ -0,0 +1,62 @@
+"""
+alembic/env.py — Alembic 运行环境配置
+从环境变量读取 DATABASE_URL，不硬编码。
+"""
+
+import os
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+# ── 确保 app 包可导入 ────────────────────────────────
+import sys
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+from app.core.database import Base
+import app.models  # noqa: F401 — 触发所有模型注册
+
+config = context.config
+
+# 从环境变量覆盖 DATABASE_URL
+db_url = os.environ.get("DATABASE_URL")
+if db_url:
+    config.set_main_option("sqlalchemy.url", db_url)
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+        )
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()