🐛 fix(ci): enable BDD_SCHEMA_ISOLATION to prevent flaky AuthBDD failures

ADR-0025 introduces per-scenario schema isolation via the BDD_SCHEMA_ISOLATION env
var. CI was running without this flag, causing scenarios to share the public
schema and pollute each other's state.

Observed flakiness: identical code passes in workflow run #605 and fails in #606
on TestAuthBDD/User_completes_password_reset, JWT_token_validation, etc.

Per ADR-0025 audit (PR #24): schema-per-scenario infrastructure is fully
implemented but disabled by default (opt-in). Enabling it in CI should resolve
the flakiness without code changes.

Diagnosed during the autonomous trainer day (2026-05-03) after observing #605
PASS / #606 FAIL on the same SHA.

🤖 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci-cd.yaml

@@ -219,6 +219,10 @@ jobs:
           export DLC_DATABASE_PASSWORD=postgres
           export DLC_DATABASE_NAME=dance_lessons_coach_bdd_test
           export DLC_DATABASE_SSL_MODE=disable
+          # Enable per-scenario schema isolation (ADR-0025) to prevent flaky AuthBDD failures.
+          # Without this, scenarios share the public schema and pollute each other's state.
+          # Observed flakiness: same code passes in #605, fails in #606 on TestAuthBDD/*.
+          export BDD_SCHEMA_ISOLATION=true
           ./scripts/run-bdd-tests.sh
           
           # Generate BDD coverage report