✨ feat: implement schema-per-scenario isolation for BDD tests

- Add BDD_SCHEMA_ISOLATION env var to enable schema-per-scenario mode
- Generate unique schema names using SHA256 hash of feature+scenario
- Implement SetupScenarioSchema() and TeardownScenarioSchema() methods
- Handle search_path configuration for schema isolation
- Use CASCADE drop to clean up all scenario-created DB objects
- Add isSchemaIsolationEnabled() helper to suite.go
- Update cleanup flow: skip table clearing when schema isolation is active
- Add ADR 0025 documenting isolation strategies and decision rationale

Activation: Set BDD_SCHEMA_ISOLATION=true to enable
Debug: Set BDD_ENABLE_CLEANUP_LOGS=true for verbose isolation logging

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

adr/README.md

@@ -30,6 +30,7 @@ This directory contains Architecture Decision Records (ADRs) for the dance-lesso
 | 0022 | Rate Limiting and Cache Strategy | ✅ Accepted |
 | 0023 | Config Hot Reloading | 🟡 Proposed |
 | 0024 | BDD Test Organization and Isolation | 🟡 Proposed |
+| 0025 | BDD Scenario Isolation Strategies | 🟡 Proposed |
 
 ## What is an ADR?
 
@@ -111,6 +112,7 @@ Chosen option: "[Option 1]" because [justification]
 * [0021-jwt-secret-retention-policy.md](0021-jwt-secret-retention-policy.md) - JWT Secret Retention Policy with Configurable TTL and Retention
 * [0022-rate-limiting-cache-strategy.md](0022-rate-limiting-cache-strategy.md) - Rate Limiting and Cache Strategy with Multi-Phase Implementation
 * [0023-config-hot-reloading.md](0023-config-hot-reloading.md) - Config Hot Reloading Strategy
+* [0025-bdd-scenario-isolation-strategies.md](0025-bdd-scenario-isolation-strategies.md) - Schema-per-scenario isolation for BDD tests
 
 ## How to Add a New ADR