feat: merge cartsnitch/api into api/ subdirectory

Consolidate API gateway service into monorepo.
Squashed from https://github.com/cartsnitch/api main (89bacb1).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/cartsnitch_api/auth/jwt.py

@@ -0,0 +1,31 @@
+"""JWT token creation and validation."""
+
+from datetime import UTC, datetime, timedelta
+from typing import Any, cast
+from uuid import UUID
+
+from jose import JWTError, jwt
+
+from cartsnitch_api.config import settings
+
+
+def create_access_token(user_id: UUID) -> str:
+    expire = datetime.now(UTC) + timedelta(minutes=settings.jwt_access_token_expire_minutes)
+    payload = {"sub": str(user_id), "exp": expire, "type": "access"}
+    return cast(str, jwt.encode(payload, settings.jwt_secret_key, algorithm=settings.jwt_algorithm))
+
+
+def create_refresh_token(user_id: UUID) -> str:
+    expire = datetime.now(UTC) + timedelta(days=settings.jwt_refresh_token_expire_days)
+    payload = {"sub": str(user_id), "exp": expire, "type": "refresh"}
+    return cast(str, jwt.encode(payload, settings.jwt_secret_key, algorithm=settings.jwt_algorithm))
+
+
+def decode_token(token: str) -> dict:
+    try:
+        return cast(
+            dict[str, Any],
+            jwt.decode(token, settings.jwt_secret_key, algorithms=[settings.jwt_algorithm]),
+        )
+    except JWTError as e:
+        raise ValueError(f"Invalid token: {e}") from e