v1.5.0: Opt-in libSQL / Turso Storage & Serverless Gateway

What's New in v1.5.0

• Opt-in libSQL / Turso Storage Engine: Dual-storage abstraction (storage/turso.py and storage/local.py) enabling remote libSQL transactions for ephemeral/serverless environments without local state dependencies. Zero configuration changes for existing local SQLite users.
• Serverless FastAPI Gateway: gateway.serverless:create_app introduces a lightweight, production-ready serverless gateway with project-scoped isolation, Porter FTS5 memory indexing, and authenticated reads via X-Friday-Key and IAM token support (FRIDAY_GCP_IAM=true).
• Migration & Runbook Tooling: Integrated snapshot exporter (scripts/migration/export_current_state.py), Turso importer, and comprehensive qualification test harness documented in docs/serverless-migration.md.
• Backwards-Compatible & Zero Breaking Changes: Default Docker Compose setup and existing MCP tools remain 100% untouched and functional.