feat: adopt kumo green ui system

.trellis/spec/frontend/components.md

@@ -97,6 +97,26 @@ export function InteractiveWidget({ initialData }: { initialData: Data }) {
 
 ## Semantic HTML
 
+## Kumo UI Convention
+
+Use `components/ui/*` as the project-owned adapter layer for Cloudflare Kumo components.
+Feature modules and route files should import `Button`, `Input`, `Select`, `Textarea`, `Table`,
+`Checkbox`, `Badge`, `Card`, and `Dialog` from `@/components/ui/...` instead of importing
+`@cloudflare/kumo` directly.
+
+```typescript
+// Good: project adapter keeps Kumo API differences local
+import { Select } from "@/components/ui/select";
+import { Table } from "@/components/ui/table";
+
+// Avoid: feature code should not hand-style native controls
+<select name="roleId" />
+<table />
+```
+
+Visible form controls and data tables should use the Kumo-backed adapters. Native hidden
+inputs are acceptable only inside adapters when needed to preserve FormData semantics.
+
 ### Use Proper Elements
 
 ```typescript