Add backend and frontend skeleton

app/backend/core/__init__.py

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+"""Core infrastructure (config, database, etc.)."""

app/backend/core/config.py

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+"""Environment configuration derived from environment variables."""
+
+from functools import lru_cache
+
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    """Application settings."""
+
+    service_name: str = "backend"
+    environment: str = "development"
+    database_url: str = (
+        "postgresql+psycopg://postgres:postgres@postgres:5432/avaaz"
+    )
+
+    model_config = SettingsConfigDict(env_prefix="", case_sensitive=False)
+
+
+@lru_cache(maxsize=1)
+def get_settings() -> Settings:
+    """Return cached settings instance."""
+    return Settings()

app/backend/core/database.py

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+"""Database connection placeholders."""
+
+from contextlib import contextmanager
+from typing import Iterator
+
+
+@contextmanager
+def get_db() -> Iterator[None]:
+    """
+    Yield a database session placeholder.
+
+    Replace with a real session (e.g., SQLAlchemy) when persistence is added.
+    """
+    yield None