feat: Pipedrive CRM integration (#64)

[Empreiteiro]

Summary

• Add Pipedrive CRM as a new data source with 12 tables (persons, organizations, deals, activities, products, deal_products, pipelines, stages, leads, notes + 2 derived timeline tables)
• 6 pre-configured report templates: Sales Pipeline, Sales Performance, Activity Tracking, Lead & Contact Analysis, Product Performance, Forecast
• Backend: ask_pipedrive.py Q&A script + pipedrive_router.py for connection testing and discovery
• Frontend: PipedriveSourceForm.tsx with test connection, resource discovery, and i18n (EN/PT/ES)

Test plan

• Test connection with valid Pipedrive API token
• Verify resource discovery shows correct counts
• Create source and ask a question about deals
• npm run typecheck passes

Closes #64

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