feat: add points system for scan types with shop purchases

[axv2655]

Summary

• Add a points system to scans: each scan type has configurable points that are awarded on scan. Admins can see/edit points per scan type in the scan types table.
• Add a new "shop" scan category that deducts points from a user's balance (repeatable, with atomic balance checking via advisory locks). Returns 402 if insufficient points.
• Add a configurable points name setting (super admin) so the display label (e.g. "HackBucks") is customizable. Shown in the scanner dialog after scans.
• Display user point balances in the applications table, application detail panel, and hacker profile page.

Backend changes

• New points column on scans table (migration 24), repeatable boolean + partial unique index (migration 25)
• CreatePurchase store method with pg_advisory_xact_lock for atomic balance verification
• GetTotalPointsByUserID store method for balance lookups
• GetPointsName / SetPointsName settings endpoints (/points-name, /superadmin/settings/points-name)
• Application endpoints now include points in responses

Frontend changes

• Scan types table: editable points column
• PointsNameCard: inline editor for super admins to rename the points system
• ScannerDialog: shows points awarded/deducted and remaining balance after scan
• Applications table & detail panel: points badge
• Hacker profile page: points display