feat: implement customizable funnel stages per tenant

- Modified attendances.funnel_stage in DB from ENUM to VARCHAR.

- Created tenant_funnels table and backend API routes to manage custom stages.

- Added /admin/funnels page for Admins/Managers to create, edit, order, and color-code their funnel stages.

- Updated Dashboard, UserDetail, and AttendanceDetail to fetch and render dynamic funnel stages instead of hardcoded enums.

- Added defensive checks and logging to GET /users/:idOrSlug to fix sporadic 500 errors during impersonation handoffs.

debug.txt

@@ -0,0 +1,12 @@
+Look at line 354: `if (req.user.role !== 'super_admin' && rows[0].tenant_id !== req.user.tenant_id) {`
+What if `req.user.tenant_id` is null (which it is for some system admins)?
+But `rows[0].tenant_id` could be something else. That just returns 403.
+What if `rows` is empty?
+Line 353: `if (rows.length === 0) return res.status(404).json({ error: 'Not found' });`
+What if `req.user` is undefined? (Should be caught by middleware).
+
+Wait, the user says the error is:
+`https://fasto.blyzer.com.br/api/users/u_71657ec7`
+And it returns `500`.
+
+Let's log the exact error inside the catch block in the backend.