feat(azure): Event Hubs in Cloud Explorer

[hectorvent]

Add Event Hubs to the Cloud Explorer (azure)

The azure emulator implements Event Hubs (~0 operations). The UI does not surface it yet.

Backend (packages/api)

• src/cloud-spi/eventhubsSchema.ts — eventhubsSchemaFor('azure') (model: src/cloud-spi/storageSchema.ts)
• src/adapter-azure/AzureEventHubsAdapter.ts implements CloudServiceAdapter + AzureEventHubsAdapter.test.ts (model: src/adapter-aws/AwsStorageAdapter.ts)
• Register new AzureEventHubsAdapter() in src/cloudProxy.ts; add services.push({...}) + schema() fallback in src/service/CloudProxyService.ts

Frontend (packages/frontend)

• Verify nav shows Event Hubs for azure and normalizeService() handles the literal (pages/CloudExplorerPage.tsx)
• Confirm generic DynamicResourceView rendering; add a service === '...' panel only if deep UX is needed

Acceptance

• Event Hubs appears in the azure nav; list / create / delete / inspect work against the local emulator
• Adapter unit test passes

Depends on #66 (new messaging service type).
Emulator source: floci-az/src/main/java/io/floci/az/services/eventhubs/