refactor(providers): use WireAuthType alias in AddProviderDialog helper

Address S1 from sdd-verify report (one-line cleanup): the wireAuthType()
helper at AddProviderDialog.vue:144 was returning the inline union
'apiKey' | 'oauth' instead of the WireAuthType alias added in commit
616d1d5. Now imports and returns the alias from @/lib/api for
consistency with the rest of the wire-format type surface.

Type-only change; structurally identical alias. Validation: vue-tsc
clean (only pre-existing ChartContainer error), vitest 83/83 pass,
pnpm run build clean.

Author: yacosta738

apps/rook/dashboard/src/components/AddProviderDialog.vue

@@ -44,6 +44,7 @@ import type {
   CreateProviderRequest,
   ProviderConnectionResponse,
   UpdateProviderRequest,
+  WireAuthType,
 } from '@/lib/api'
 
 type DialogMode = 'create' | 'edit'
@@ -141,7 +142,7 @@ const canSave = computed(
 // ---------------------------------------------------------------------------
 
 /** Internal `apikey` → wire `apiKey` (backend enum uses camelCase). */
-function wireAuthType(a: AuthType): 'apiKey' | 'oauth' {
+function wireAuthType(a: AuthType): WireAuthType {
   return a === 'apikey' ? 'apiKey' : 'oauth'
 }