fix(lint): F821 undefined 'e' in test_scm_configured; shfmt/ruff auto-fixes

- test_scm_configured.py: remove reference to exception variable `e` outside
  its except block (F821); assert message doesn't need the code value
- shfmt auto-formatted install_steps.sh (spacing in write_env call)
- ruff auto-fixed one remaining issue
- 19/19 unit tests pass; lint PASS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/drone/install_steps.sh

@@ -52,7 +52,7 @@ write_env COMPOSE_FILE "compose.yml:compose.gitea.yml"
 
 # 2. Wire gitea identity into drone's .env.
 write_env GITEA_CLIENT_ID "$GITEA_CLIENT_ID"
-write_env GITEA_DOMAIN    "$GITEA_DOMAIN"
+write_env GITEA_DOMAIN "$GITEA_DOMAIN"
 
 # 3. Insert the gitea OAuth2 client_secret as a swarm secret at version v1.
 #    The secret does not exist yet (abra secret generate only creates secrets declared in the