Add discovery search history with auto-save, fix timeout causing search failure

- Save every search result to DB for later review
- Add '搜索历史' tab with timeline view, load/delete records
- Raise discovery search timeout from 30s to 120s (Bing Puppeteer needs ~40s)
- Reduce search queries from 4 to 3 for faster response
- New model: DiscoveryRecord (user_id, product, market, companies JSON)
- API: POST/GET/DELETE /api/v1/discovery/records
- Migration: discovery_records table

backend/app/main.py

@@ -54,7 +54,7 @@ async def health():
     return {"status": "ok", "app": settings.APP_NAME, "version": "1.0.0"}
 
 
-from app.api.v1 import auth, marketing, translate, customer, quotation, whatsapp, product, exchange, push, admin, analytics, teams, onboarding, notification, feedback, payment, interaction, silent_pattern, training, followup, ai_assistant, discovery, certification, invoice, usage, referral, admin_search, search
+from app.api.v1 import auth, marketing, translate, customer, quotation, whatsapp, product, exchange, push, admin, analytics, teams, onboarding, notification, feedback, payment, interaction, silent_pattern, training, followup, ai_assistant, discovery, discovery_record, certification, invoice, usage, referral, admin_search, search
 
 app.include_router(auth.router, prefix="/api/v1/auth", tags=["auth"])
 app.include_router(marketing.router, prefix="/api/v1/marketing", tags=["marketing"])
@@ -79,6 +79,7 @@ app.include_router(training.router, prefix="/api/v1/training", tags=["training"]
 app.include_router(followup.router, prefix="/api/v1/followup", tags=["followup"])
 app.include_router(ai_assistant.router, prefix="/api/v1/ai", tags=["ai-assistant"])
 app.include_router(discovery.router, prefix="/api/v1/discovery", tags=["discovery"])
+app.include_router(discovery_record.router, prefix="/api/v1/discovery", tags=["discovery"])
 app.include_router(certification.router, prefix="/api/v1/certification", tags=["certification"])
 app.include_router(invoice.router, prefix="/api/v1/invoices", tags=["invoices"])
 app.include_router(usage.router, prefix="/api/v1/usage", tags=["usage"])