🔒️(backend) secure native app OIDC login with exchange codes

Add one-time exchange code mechanism for native app OIDC login.
Instead of exposing session ID in redirect URL, generates a
short-lived single-use code stored in Redis. Native apps exchange
this code for the session ID via a dedicated API endpoint.

Includes NativeAppRedirect for custom URL schemes, rate limiting,
logging, and whitelist of allowed schemes.

Closes #1153

Co-Authored-By: gigi206

bin/pytest-summary

@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-source "$(dirname "${BASH_SOURCE[0]}")/_config.sh"
-
-_dc_run \
-    app-summary-dev \
-    python -m pytest "$@"