refactor: engineering improvements -- API versioning, structured logging, Alembic, error standardization, test coverage

- API versioning: all REST endpoints prefixed with /api/v1/
- Structured logging: replaced stdlib logging with structlog (console/JSON modes)
- Alembic migrations: versioned DB schema with initial migration
- Error standardization: global exception handlers for consistent envelope format
- Interrupt cleanup: asyncio background task for expired interrupt removal
- Integration tests: +30 tests (analytics, replay, openapi, error, session APIs)
- Frontend tests: +57 tests (all components, pages, useWebSocket hook)
- Backend: 557 tests, 89.75% coverage | Frontend: 80 tests, 16 test files

backend/app/openapi/review_api.py

@@ -10,11 +10,11 @@ Exposes endpoints for:
 from __future__ import annotations
 
 import asyncio
-import logging
 import re
 import uuid
 from typing import Literal
 
+import structlog
 from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException
 from pydantic import BaseModel, field_validator
 
@@ -23,10 +23,10 @@ from app.openapi.generator import generate_agent_yaml, generate_tool_code
 from app.openapi.importer import ImportOrchestrator
 from app.openapi.models import ClassificationResult, ImportJob
 
-logger = logging.getLogger(__name__)
+logger = structlog.get_logger()
 
 router = APIRouter(
-    prefix="/api/openapi",
+    prefix="/api/v1/openapi",
     tags=["openapi"],
     dependencies=[Depends(require_admin_api_key)],
 )