fix(frontend): harden release-v5.1 Helm deployments

[mlhiter]

What this PR does

• migrates the remaining release-v5.1 provider deployments from ad hoc manifest templates to Helm charts and completes missing chart resources for existing providers
• standardizes deployment entrypoints, value precedence, probes, ingress and App URLs, runtime configuration, secrets, and Helm test hooks across frontend charts
• adds CI Helm validation plus image build coverage for cloudserver and invite, and updates the frontend deployment documentation

Verification

• helm lint and helm template passed for all 13 affected charts with default values and each chart's user values file
• bash -n passed for all modified deployment shell scripts
• node --check passed for all modified JavaScript configuration files
• git diff --check upstream/release-v5.1...HEAD passed

[pull-request-size]

Whoa! Easy there, Partner!

This PR is too big. Please break it up into smaller PRs.