✨ feat: add schema-per-scenario isolation with BDD_SCHEMA_ISOLATION env var

- Add BDD_SCHEMA_ISOLATION env var to enable PostgreSQL schema-per-scenario isolation
- Generate unique schema names: test_{sha256(feature:scenario)[:8]}
- Implement SetupScenarioSchema() and TeardownScenarioSchema() with search_path handling
- Add CASCADE drop to clean up all scenario-created DB objects
- Add isSchemaIsolationEnabled() helpers to both suite.go and server.go
- Skip table clearing when schema isolation is active (schema drop replaces it)
- Update validate-test-suite.sh to set FIXED_TEST_PORT and BDD_SCHEMA_ISOLATION
- Add isCleanupLoggingEnabled() for optional CLEANUP: prefixed logs
- Add ADR 0025 documenting all isolation strategies and decision rationale

Activation:
  BDD_SCHEMA_ISOLATION=true - Enable schema-per-scenario isolation
  BDD_ENABLE_CLEANUP_LOGS=true - Enable verbose cleanup/isolation logging

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

scripts/validate-test-suite.sh

@@ -55,6 +55,9 @@ for (( run=1; run<=$RUN_COUNT; run++ )); do
     echo "  🧪 Unit tests..."
     go clean -testcache > /dev/null 2>&1
     
+    # Set environment variables for consistent test behavior
+    export FIXED_TEST_PORT=true
+    
     set +e  # Temporarily disable exit on error
     UNIT_OUTPUT=$(go test ./cmd/... ./pkg/... -v 2>&1)
     UNIT_EXIT_CODE=$?
@@ -77,6 +80,15 @@ for (( run=1; run<=$RUN_COUNT; run++ )); do
     echo "  🧪 BDD tests..."
     go clean -testcache > /dev/null 2>&1
     
+    # Set environment variables for consistent BDD test behavior
+    export FIXED_TEST_PORT=true
+    export BDD_SCHEMA_ISOLATION=true
+    export DLC_DATABASE_HOST=localhost
+    export DLC_DATABASE_PORT=5432
+    export DLC_DATABASE_USER=postgres
+    export DLC_DATABASE_PASSWORD=postgres
+    export DLC_DATABASE_NAME=dance_lessons_coach_test
+    
     set +e  # Temporarily disable exit on error
     BDD_OUTPUT=$(go test ./features/... -v 2>&1)
     BDD_EXIT_CODE=$?
@@ -142,7 +154,7 @@ else
     # Process BDD test failures
     if [ -s "$BDD_FAILURE_LOG" ]; then
         echo "BDD Test Failures:"
-        echo "================"
+        echo "==============="
         
         # Count BDD test failures with granularity
         BDD_FAILURES=$(grep "FAIL" "$BDD_FAILURE_LOG" | \
@@ -155,7 +167,7 @@ else
             while IFS= read -r line; do
                 count=$(echo "$line" | awk '{print $1}')
                 test=$(echo "$line" | sed 's/^[0-9]*[[:space:]]*//')
-                echo "  $count × $test"
+                echo "  $count x $test"
             done <<< "$BDD_FAILURES"
         else
             echo "  None (check log for details)"
@@ -182,4 +194,4 @@ else
     echo "  5. Use ./scripts/run-bdd-tests.sh list-tags to see available tags"
     
     exit 1
-fi
+fi