feat: initialiser le projet CVP (Next.js 14 + FastAPI + PostgreSQL)

- Frontend : Next.js 14 App Router, TypeScript strict, Tailwind 3, shadcn/ui, next-intl (fr/en)
- Backend : FastAPI, SQLAlchemy 2 async, Alembic, Pydantic 2, Python 3.11
- Infrastructure : Docker Compose (PostgreSQL 16 + Ollama)
- Tooling : ESLint + Prettier (frontend), Ruff (backend), pytest
- Structure complète des dossiers avec pages et routers placeholder

backend/app/db/migrations/env.py

@@ -0,0 +1,54 @@
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+from app.config import settings
+
+# This is the Alembic Config object
+config = context.config
+
+# Set the SQLAlchemy URL from our app config
+# Use the sync version (postgresql:// instead of postgresql+asyncpg://)
+config.set_main_option(
+    "sqlalchemy.url",
+    settings.database_url.replace("+asyncpg", ""),
+)
+
+# Interpret the config file for Python logging
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# Import all models here so Alembic can detect them
+# from app.models import Base  # uncomment when models are defined
+target_metadata = None  # replace with Base.metadata when models are defined
+
+
+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()