feat(phase1): Complete development environment configuration

- Configure Alembic for database migrations with initial schema
- Fix base.py to use lazy loading for async engine (avoids import-time issues)
- Change AI model from sonnet to haiku (claude-3-haiku-20240307)
- Fix pytest version compatibility with pytest-asyncio
- Add frontend package-lock.json

Phase 1 tasks completed:
- F1.1: Development environment (Docker, Node.js 20, Python 3.12, venv)
- F1.2: PostgreSQL with 8 categories seeded
- F1.3: Redis connection verified
- F1.4: Anthropic API configured and tested
- F1.5: Backend server + WebSocket verified

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/alembic.ini

@@ -0,0 +1,42 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+
+sqlalchemy.url = postgresql://trivia:trivia@localhost:5432/trivia
+
+[post_write_hooks]
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S