fix: align playground default model id with org namespace

Opening an org-scoped deployment in the Playground pre-selected the bare
model name (e.g. `qwen3-0.6b`), which never matched the org-namespaced
option the `/v1/models` dropdown actually lists (`org1/qwen3-0.6b`), so
the selection showed an unmatched value.

Resolve the owning org from the route row's `owner_principal_id` (falling
back to the org the caller is currently acting under for the admin "All"
view) and reconstruct the same `{org}/{name}` id the server reports. The
platform org carries no prefix, matching the server's behaviour.

- user.ts: add `getOrgById`/`getCurrentOrg` that scan both org caches
  (`organizationList` + admin-only `allOrganizations`) with string-
  normalised id comparison; `getOrgNameById` is now a thin wrapper.
  Helpers accept `undefined` so optional row fields type-check.
- use-open-playground: build the prefix from the resolved org record,
  keying the skip-prefix decision off `is_platform`.
- RouteItem: declare the `owner_principal_id` the list API returns.
- RouteTargetFormItem: drop the duplicate `overridden_model_name`
  declaration that TS flagged as a duplicate identifier.

src/pages/model-routes/config/types.ts

@@ -4,7 +4,6 @@ export interface RouteTargetFormItem {
   weight?: number | null;
   model_id?: number;
   provider_id?: number;
-  overridden_model_name?: string;
   fallback_status_codes?: string[];
   parentId?: string | number;
 }
@@ -32,6 +31,9 @@ export interface RouteItem {
   targets: number;
   ready_targets: number;
   access_policy: string;
+  // Org principal that owns this route. Drives the ``{org}/{name}`` model-id
+  // prefix when opening the route in the Playground.
+  owner_principal_id?: number;
 }
 
 export interface RouteTarget extends RouteTargetFormItem {