feat(ui): add identity management for tenants and users

* Implement tenant and user creation in IdentityPage
* Add API calls for managing tenants and users
* Introduce tenant-scoped API requests
* Update sidebar to include identity navigation
* Create BooleanStatusBadge component for key status

schema/core.dbml

@@ -6,12 +6,12 @@ Table thoughts {
   created_at timestamptz [default: `now()`]
   updated_at timestamptz [default: `now()`]
   project_id bigint [ref: > projects.id]
-  tenant_key text
+  tenant_id text [ref: > tenants.id]
   archived_at timestamptz
 
   indexes {
-    tenant_key
-    (tenant_key, project_id)
+    tenant_id
+    (tenant_id, project_id)
   }
 }
 
@@ -20,13 +20,13 @@ Table projects {
   guid uuid [unique, not null, default: `gen_random_uuid()`]
   name text [not null]
   description text
-  tenant_key text
+  tenant_id text [ref: > tenants.id]
   created_at timestamptz [default: `now()`]
   last_active_at timestamptz [default: `now()`]
 
   indexes {
-    (tenant_key, name) [unique]
-    tenant_key
+    (tenant_id, name) [unique]
+    tenant_id
   }
 }