feat: add multi-company Feishu integration and data migration

- Add companies table enhancements (abbr, tenant_key, feishu_enabled)
- Add users table enhancements (feishu fields, sn, report_to, etc.)
- Create company_feishu_apps table for multi-app per company
- Create user_sn_pool table for user number management
- Update FeishuService to support multiple Feishu apps per company
- Add data migration script (002_merge_old_data.sql)
- Add import script (scripts/import_old_data.php)
- Update User and Company models with new scopes and relationships
- Add CompanyFeishuApp model
- Add Git workflow documentation (GIT_WORKFLOW.md)

This supports:
- Multi-company architecture with Feishu integration
- Multiple Feishu apps per company (X-Server, Ticket, CRM)
- User number assignment system
- Data migration from old project

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -48,3 +48,7 @@ docker-volumes/
 # Lock files (optional - uncomment if you want to exclude)
 # package-lock.json
 # composer.lock
+
+# Large SQL files (import data files)
+*.sql
+!database/migrations/*.sql