docs: improve deployment guidance

[krider2010]

Summary

This PR addresses current customer feedback around deployment discoverability and production guidance:

• documents the existing ECS/Fargate CloudFormation deployment path and makes it discoverable from the root README
• parameterizes ECS worker/main scaling defaults and worker concurrency without changing current behavior
• adds a Helm HTTPS ingress example with TLS, sticky sessions, and webhook processor routing
• documents existing Helm support for TLS, ports, health checks, sticky sessions, HPA/KEDA, and why workers do not have a Service
• adds the new HTTPS ingress example to CI template validation

Azure Container Apps ARM/Bicep support is intentionally out of scope for this repository change.

Validation

• helm lint charts/n8n
• helm template test charts/n8n -f charts/n8n/examples/https-ingress.yaml --dry-run=client
• helm template test charts/n8n -f charts/n8n/examples/production-s3.yaml --dry-run=client
• full Helm example render matrix
• cfn-lint --non-zero-exit-code error aws-cloudformation/ecs-fargate/n8n-w-multimain-queuemode.yaml
• git diff --check

cfn-lint still reports warnings already present on origin/main; this change does not introduce new CloudFormation lint findings.