Senior Full Stack Developer for White Label CRM Build

UK web studio looking for a senior full stack developer to build a custom CRM for one of our clients, white label under our agency. They're on spreadsheets and a shared inbox today and want everything in one place: contacts, leads and job history, jobs moving through stages, role-based logins for admin, office and field staff, AI for summarising enquiries and drafting replies, email and calendar integration, simple reporting, hosted and deployed. Tech is your call, but no no-code tools. We handle the client and the design, you handle the build. Two more clients likely to need the same if this goes well. UK hours preferred.