Implement Alembic for database migrations and update FastAPI initialization

- Integrate Alembic for managing database schema migrations, replacing the previous SQL schema management.
- Update the FastAPI application to synchronize interface definitions at startup.
- Modify the Docker Compose command to run Alembic migrations before starting the API.
- Enhance the Makefile with new commands for database migration and revision management.
- Remove outdated SQL schema and seed files, transitioning to a more dynamic migration approach.
- Add initial migration scripts and configuration for Alembic, ensuring a structured database evolution.

backend/db/session.py

@@ -2,14 +2,13 @@
 
 - engine / SessionLocal:全局单例
 - get_session:FastAPI 依赖,按请求注入一个会话
-- init_db:启动时建表(MVP 用 create_all;表结构稳定后切 alembic 迁移,对齐 dograh)
+- sync_interface_definitions:启动时同步接口定义;表结构由 Alembic 管理
 """
 
 from collections.abc import AsyncGenerator
 import json
 
 import config
-from db.models import Base
 from services.interface_catalog import INTERFACE_DEFINITIONS
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import (
@@ -27,15 +26,8 @@ async def get_session() -> AsyncGenerator[AsyncSession, None]:
         yield session
 
 
-async def init_db() -> None:
+async def sync_interface_definitions() -> None:
     async with engine.begin() as conn:
-        await conn.run_sync(Base.metadata.create_all)
-        await conn.execute(
-            text(
-                "ALTER TABLE interface_definitions "
-                "ALTER COLUMN field_schema TYPE JSONB USING field_schema::jsonb"
-            )
-        )
         for definition in INTERFACE_DEFINITIONS:
             await conn.execute(
                 text(