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/identity.dbml

@@ -0,0 +1,33 @@
+Table tenants {
+  id         text        [pk]
+  name       text        [not null, unique]
+  created_at timestamptz [not null, default: `now()`]
+}
+
+Table tenant_users {
+  id         text        [pk]
+  tenant_id  text        [not null, ref: > tenants.id]
+  name       text        [not null]
+  email      text
+  created_at timestamptz [not null, default: `now()`]
+
+  Indexes {
+    tenant_id
+    (tenant_id, email) [unique]
+  }
+}
+
+Table api_key_assignments {
+  key_id      text        [pk]
+  tenant_id   text        [not null, ref: > tenants.id]
+  user_id     text        [ref: > tenant_users.id]
+  description text        [not null, default: '']
+  source      text        [not null]
+  enabled     boolean     [not null, default: true]
+  created_at  timestamptz [not null, default: `now()`]
+}
+
+Table managed_api_keys {
+  key_id      text        [pk, ref: > api_key_assignments.key_id]
+  secret_hash text        [not null]
+}