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/skills.dbml

@@ -1,7 +1,8 @@
 Table agent_skills {
   id bigserial [pk]
   guid uuid [unique, not null, default: `gen_random_uuid()`]
-  name text [unique, not null]
+  name text [not null]
+  tenant_id text [ref: > tenants.id]
   description text [not null, default: '']
   content text [not null]
   tags "text[]" [not null, default: `'{}'`]
@@ -11,18 +12,23 @@ Table agent_skills {
   domain_tags "text[]" [not null, default: `'{}'`]
   created_at timestamptz [not null, default: `now()`]
   updated_at timestamptz [not null, default: `now()`]
+
+  indexes { (tenant_id, name) [unique] tenant_id }
 }
 
 Table agent_guardrails {
   id bigserial [pk]
   guid uuid [unique, not null, default: `gen_random_uuid()`]
-  name text [unique, not null]
+  name text [not null]
+  tenant_id text [ref: > tenants.id]
   description text [not null, default: '']
   content text [not null]
   severity text [not null, default: 'medium']
   tags "text[]" [not null, default: `'{}'`]
   created_at timestamptz [not null, default: `now()`]
   updated_at timestamptz [not null, default: `now()`]
+
+  indexes { (tenant_id, name) [unique] tenant_id }
 }
 
 Table project_skills {