Move the Azure infrastructure to the SSW Azure subscription

Problem

SSW.Walrus is currently deployed to a personal/staging Azure subscription (rg-walrus-staging, acrwalrusstaging, func-walrus-staging, sawalrusstaging / sawalrusstagingweb). It needs to run on SSW-owned Azure so it's not tied to a personal account.

Goal

Deploy the whole Walrus stack under the SSW Azure subscription/tenant with SSW-owned identity and secrets.

Acceptance criteria

• Infra (infra/main.bicep) deployed into an SSW resource group under the SSW subscription.
• GitHub OIDC federated credential re-created against the SSW tenant; repo AZURE_CLIENT_ID / AZURE_TENANT_ID / AZURE_SUBSCRIPTION_ID vars updated so azure-deploy.yml deploys to SSW.
• Key Vault secrets re-provisioned in the SSW vault (anthropic-oauth-token, elevenlabs-api-key — see linked issue).
• Container App Job env (DASHBOARD_STORAGE_ACCOUNT, DASHBOARD_BASE_URL, LOGBOOK_VOICE) updated for the SSW resources.
• A full run (ingest → dashboard → deploy → email) verified end-to-end on SSW infra.
• Personal-subscription resources decommissioned once cutover is confirmed.

Notes

• Blocks / relates to the Power Automate move (connections point at the SSW storage account) and the ElevenLabs key.