Use - as hash delimiter instead

app/config.py

@@ -34,7 +34,8 @@ def _hash_password(pw: str) -> str:
         salt = os.urandom(16)
         iterations = 200_000
         dk = hashlib.pbkdf2_hmac('sha256', pw.encode('utf-8'), salt, iterations)
-        return f"pbkdf2_sha256${iterations}${binascii.hexlify(salt).decode()}${binascii.hexlify(dk).decode()}"
+        # use - as the delimiter to avoid Docker env variable substitution
+        return f"pbkdf2_sha256-{iterations}-{binascii.hexlify(salt).decode()}-{binascii.hexlify(dk).decode()}"
     except Exception:
         return ""