Table Editor silently modifies tenant_id when editing composite FK columns

# Bug report - [x] I confirm this is a bug with Supabase, not with my own application. - [x] I confirm I have searched the [Docs](https://docs.supabase.com), GitHub [Discussions](https://github.com/orgs/supabase/discussions), and [Discord](https://discord.supabase.com). ## Describe the bug The Table Editor silently modifies `tenant_id` when editing a foreign key column that's part of a composite FK constraint. This allows records to move between tenants without user consent, bypassing tenant isolation. **Core issue:** When editing a single cell (e.g., `role_id`), the UI automatically updates another column (`tenant_id`) to satisfy the composite FK. This is inconsistent with editing `tenant_id` directly, which correctly shows an FK error. **Related but separate from:** [#41068](https://github.com/supabase/supabase/issues/41068) (visual FK picker bug). This issue is about UPDATE operations silently bypassing composite FK constraints. ## To Reproduce ### 1. Schema setup ```sql -- Multi-tenant schema with composite FK CREATE TABLE tenants ( tenant_id text PRIMARY KEY, name text ); CREATE TABLE roles ( role_id text PRIMARY KEY, -- Globally unique (would be UUID in production) tenant_id text REFERENCES tenants(tenant_id), role_name text, UNIQUE (role_id, tenant_id) -- For composite FK ); CREATE TABLE employees ( employee_id text PRIMARY KEY, -- Globally unique tenant_id text REFERENCES tenants(tenant_id), role_id text, name text, FOREIGN KEY (role_id, tenant_id) REFERENCES roles(role_id, tenant_id) ); ``` **Key points:** - `role_id` is globally unique (PK), not per-tenant - `tenant_id` is NOT part of the PK - used only for tenant isolation - Each role belongs to exactly ONE tenant ### 2. Test data ```sql INSERT INTO tenants VALUES ('tenant-A', 'Tenant A'), ('tenant-B', 'Tenant B'); INSERT INTO roles VALUES ('role-1', 'tenant-A', 'Admin'), -- role-1 belongs to tenant-A ('role-2', 'tenant-B', 'Manager'), -- role-2 bel…