feat(argo-workflows): add deploymentStrategy values for controller and server

[joestadler]

Why

The workflow-controller Deployment and the argo-server Deployment didn't expose a way to set spec.strategy. The controller template only set type: Recreate when replicas == 1; otherwise no strategy was rendered on either Deployment, so Kubernetes fell back to the default RollingUpdate { maxUnavailable: 25%, maxSurge: 25% }.

For operators running 2 replicas, that default allows an old pod to terminate before its replacement is Ready, producing a brief gap that surfaces to users as a white screen during chart upgrades. A PDB doesn't help here — PDBs only govern voluntary disruptions (drains), not rolling updates. The argo-cd chart already exposes deploymentStrategy per component for exactly this reason; this PR brings argo-workflows in line.

What

Adds controller.deploymentStrategy and server.deploymentStrategy values (default {}). When set, the value is rendered into spec.strategy on the corresponding Deployment.

Backwards compatible:

• controller.deploymentStrategy: {} (default) + controller.replicas: 1 → unchanged: type: Recreate is rendered (preserves the behavior added in https://github.com/argoproj/argo-helm/blob/main/charts/argo-workflows/templates/controller/workflow-controller-deployment.yaml).
• controller.deploymentStrategy: {} + controller.replicas >= 2 → unchanged: no strategy rendered, K8s default applies.
• server.deploymentStrategy: {} (default) → unchanged: no strategy rendered.

New capability: operators running 2+ replicas can now opt into zero-downtime rolls:

controller:
  replicas: 2
  deploymentStrategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 0
      maxSurge: 1
server:
  replicas: 2
  deploymentStrategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 0
      maxSurge: 1

Verified locally with helm template:

Scenario	Controller strategy	Server strategy
Defaults (replicas=1, no override)	type: Recreate	(none)
replicas=2, no override	(none)	(none)
replicas=2 + override	RollingUpdate maxUnavailable=0	RollingUpdate maxUnavailable=0

Checklist

• Bumped chart version: 1.0.13 → 1.0.14
• Updated README.md via ./scripts/helm-docs.sh
• Updated artifacthub.io/changes annotation in Chart.yaml
• New values are backwards compatible with sensible defaults ({})
• Commits are DCO signed
• Single chart in this PR (argo-workflows only)