Chart publish: include ingestor subchart in release workflow + CI lint

[saadqbal]

Problem

The customer-facing install command is:

helm repo add tracebloc https://tracebloc.github.io/client
helm install my-dataset tracebloc/ingestor \
  --namespace tracebloc-templates \
  --set-file ingestConfig=./my-ingest.yaml

For tracebloc/ingestor to resolve, the ingestor subchart must be in the gh-pages helm repo. Today it isn't. release-helm-chart.yaml only packages ./client:

- name: Package tracebloc chart
  id: package
  run: |
    helm package ./client
    TGZ=$(ls -t client-*.tgz | head -1)

The result: the parent client chart publishes, but helm install tracebloc/ingestor ... returns Error: chart "ingestor" not found. The first customer to try the documented install path is blocked.

Similarly, helm-ci.yaml only lints ./client on PRs, so any future syntax break in ingestor/templates/*.yaml would land on develop without CI noticing.

Scope

Three changes in one PR:

1. release-helm-chart.yaml: package + index BOTH charts.
2. helm-ci.yaml: lint BOTH charts on every PR.
3. ingestor/Chart.yaml: bump appVersion: "0.3.0-rc1" → "0.3.0" to match the data-ingestors v0.3.0 release that just shipped (https://github.com/tracebloc/data-ingestors/releases/tag/v0.3.0). This is pure documentation hygiene; the chart version (0.2.0) is correct already.

Acceptance criteria

• After release: helm repo update && helm install <name> tracebloc/ingestor ... resolves and succeeds.
• After PR merge: helm-ci.yaml runs helm lint --strict ./ingestor alongside the existing ./client lint, fails CI if either is broken.
• tracebloc.github.io/client/index.yaml contains both client and ingestor entries.

Validated by

End-to-end real-cluster smoke test today (2026-05-20) confirmed the chart works correctly when installed from local path. Publishing is the last gate before customer-accessible install.