Helm chart 0.1.0: generic chart with Tuist-specific config split into overlay

The 0.1.0 Helm chart for Hive no longer carries Tuist-specific defaults, so it can be installed by anyone to deploy their own Hive instance. Host, image pull secret, External Secrets Operator wiring, and the Postgres S3 backup are left unset by default, and a new secrets.existingSecret value lets operators mount their own Kubernetes Secret for SECRET_KEY_BASE and OAuth credentials. Tuist’s production configuration (hive.tuist.dev host, ghcr-pull image pull secret, 1Password-backed External Secrets for Google OAuth, hcloud-volumes storage, and the S3 backup endpoint) is moved into a separate values-production.yaml overlay that the deploy workflow applies via helm upgrade --values. A plain helm template hive infra/helm/hive now renders zero references to Tuist, 1Password, or hcloud.