refactor: reorganize project structure and update configurations

- Move migrations/ to database/schema/ for clarity on database schema definitions
- Move sqlc.yaml to internal/database/ to group with database code
- Move static/ to cmd/server/static/ to co-locate with server
- Update all configuration files and documentation
- Follow Go project conventions for better organization

database/schema/007_add_scan_settings.up.sql

@@ -0,0 +1,3 @@
+-- Add scan settings to users table
+ALTER TABLE users ADD COLUMN scan_frequency_minutes INTEGER DEFAULT 60;
+ALTER TABLE users ADD COLUMN auto_scan_enabled BOOLEAN DEFAULT true;