refactor(charts): tier-1 consistency pass across the chart collection

[somaz94]

What

Consistency / DRY quick-wins across the chart collection (Tier 1 of the refactor plan). Three charts get a patch bump for packaging-relevant changes; the rest are packaging-neutral (verified render/behavior-identical).

Changes

Packaging-neutral (no version bump):

• fix(scripts): normalize all 5 chart upgrade.sh shebangs to #!/usr/bin/env bash (was #!/bin/bash). upgrade.sh is .helmignore-excluded, so no tarball impact.
• docs(charts): backfill _helpers.tpl doc-comments in postgresql and redis to match the documented mysql style. Verified render-identical (helm template before/after byte-equal — comments never render).

Packaging changes (patch bump + CHANGELOG):

• fix(charts): exclude ci/ from the elasticsearch-eck and kibana-eck package tarballs via .helmignore (CI-only values, matching ghost/unity-mcp-server). → es 0.1.13, kibana 0.1.6.
• refactor(metallb-cr): dedupe values.schema.json via $defs.stringMap + $defs.specExtra (matches the keycloak-cr/keycloak-operator convention). Proven behavior-identical — resolving every $ref and dropping $defs yields the exact prior schema. → metallb-cr 0.1.2.

Also carries a maintainer housekeeping commit removing the now-obsolete DCO sign-off instructions from CONTRIBUTING.md / the PR template.

Not included

• Component-label helper parametrization (🟢) is deferred to the Tier 3 type: library shared-chart work, which would rework the same helper signatures.

Verification

• helm lint + make validate (kubeconform) pass on all touched charts
• scripts/upgrade-sync/sync.sh --check → 0 drift
• Render / schema equivalence proven for the packaging-neutral changes
• CHANGELOG updated for every version-bumped chart

🤖 Generated with Claude Code

[github-actions]

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